diff --git a/electron/main/services/dmmMigration.guards.test.ts b/electron/main/services/dmmMigration.guards.test.ts
index c46870ef..14ac2617 100644
--- a/electron/main/services/dmmMigration.guards.test.ts
+++ b/electron/main/services/dmmMigration.guards.test.ts
@@ -151,6 +151,81 @@ describe('idempotency: a second run adopts nothing and mints no duplicates', ()
   });
 });
 
+describe('unknown-mod rows from startup do not count as managed', () => {
+  const sha = (content: Buffer) => createHash('sha256').update(content).digest('hex');
+
+  it('adopts shared-folder files that only carry the backfilled hash and inferred hero', async () => {
+    const sb = makeSandbox();
+    const enabledBytes = Buffer.from('DMM-ENABLED-SKIN-111');
+    const disabledBytes = Buffer.from('DMM-DISABLED-HUD-222');
+    const liveSlot = join(sb.addons, 'pak50_dir.vpk');
+    const disabledSlot = join(sb.disabled, 'hud_thing_dir.vpk');
+    writeFileSync(liveSlot, enabledBytes);
+    writeFileSync(disabledSlot, disabledBytes);
+    // What backfillMissingMetadataHashes + enrichMod leave on unknown VPKs.
+    writeFileSync(
+      join(sb.userData, 'mod-metadata.json'),
+      JSON.stringify({
+        'pak50_dir.vpk': {
+          sha256: sha(enabledBytes),
+          globalType: null,
+          globalTypeClassifierVersion: 4,
+          lockerHero: 'Mina',
+          lockerHeroVpkChecked: true,
+          abilitySounds: null,
+        },
+        'hud_thing_dir.vpk': { sha256: sha(disabledBytes), globalType: 'hud', globalTypeClassifierVersion: 4 },
+      })
+    );
+    writeState(sb, [
+      { id: 111, name: 'Enabled Skin', enabled: true, vpks: [liveSlot] },
+      { id: 222, name: 'Hud Thing', enabled: false, vpks: [disabledSlot] },
+    ]);
+
+    const addonsBefore = fileNames(sb.addons);
+    const report = await run(sb);
+    expect(report.adopted.map((a) => a.submissionId).sort()).toEqual([111, 222]);
+    const meta = JSON.parse(readFileSync(join(sb.userData, 'mod-metadata.json'), 'utf-8'));
+    expect(meta['pak50_dir.vpk'].gameBananaId).toBe(111);
+    expect(meta['hud_thing_dir.vpk'].gameBananaId).toBe(222);
+    // Adopted in place: no extra slot, no copy.
+    expect(fileNames(sb.addons)).toEqual(addonsBefore);
+  });
+
+  it('a hero the user assigned by hand still protects the file', async () => {
+    const sb = makeSandbox();
+    const bytes = Buffer.from('USERS-OWN-SKIN');
+    const liveSlot = join(sb.addons, 'pak50_dir.vpk');
+    writeFileSync(liveSlot, bytes);
+    writeFileSync(
+      join(sb.userData, 'mod-metadata.json'),
+      JSON.stringify({ 'pak50_dir.vpk': { sha256: sha(bytes), lockerHero: 'Mina', lockerHeroSource: 'manual' } })
+    );
+    writeState(sb, [{ id: 111, name: 'Enabled Skin', enabled: true, vpks: [liveSlot] }]);
+
+    const report = await run(sb);
+    expect(report.adopted).toEqual([]);
+    expect(report.skipped[0].reason).toContain('already managed');
+  });
+
+  it('identifies an unknown twin instead of copying the same bytes again', async () => {
+    const sb = makeSandbox();
+    const bytes = Buffer.from('PROFILE-COPY-333');
+    const profileVpk = join(sb.separate, 'pak01_dir.vpk');
+    const twin = join(sb.addons, 'pak50_dir.vpk');
+    writeFileSync(profileVpk, bytes);
+    writeFileSync(twin, bytes);
+    writeFileSync(join(sb.userData, 'mod-metadata.json'), JSON.stringify({ 'pak50_dir.vpk': { sha256: sha(bytes) } }));
+    writeState(sb, [{ id: 333, name: 'Profile Mod', enabled: true, vpks: [profileVpk] }]);
+
+    const addonsBefore = fileNames(sb.addons);
+    const report = await run(sb);
+    expect(report.adopted.map((a) => [a.submissionId, a.installedAs])).toEqual([[333, 'pak50_dir.vpk']]);
+    expect(fileNames(sb.addons)).toEqual(addonsBefore);
+    expect(existsSync(profileVpk)).toBe(true);
+  });
+});
+
 describe('staleness guard: stale DMM records cannot hijack reused slots', () => {
   it('skips a bare pakNN slot that is newer than the record claiming it', async () => {
     const sb = makeSandbox();
diff --git a/electron/main/services/dmmMigration.ts b/electron/main/services/dmmMigration.ts
index 784ba371..691daf32 100644
--- a/electron/main/services/dmmMigration.ts
+++ b/electron/main/services/dmmMigration.ts
@@ -26,12 +26,14 @@ import {
   allocateEnabledVpkPath,
   makeDisabledFileName,
   runExclusiveModMutation,
+  scanMods,
 } from './mods';
 import {
   setModMetadataWithHash,
   getModMetadata,
   removeModMetadata,
   loadMetadata,
+  hasModIdentity,
   hashFileSha256,
   backupMetadataSidecar,
   type ModMetadata,
@@ -247,24 +249,6 @@ function isLiveDisabledSlot(src: string, disabledPath: string): boolean {
   return resolve(dirname(src)) === resolve(disabledPath);
 }
 
-/** Whether a metadata entry shows Grimoire already manages this VPK: a prior
- *  GameBanana install/import, a merged build, a Locker-managed surface, or a
- *  user-assigned hero. Adopting over such an entry in place would hijack a real
- *  mod's identity, so we skip it instead. */
-function isGrimoireManaged(meta: ModMetadata): boolean {
-  return (
-    meta.gameBananaId !== undefined ||
-    meta.merged !== undefined ||
-    meta.lockerCosmetics !== undefined ||
-    meta.lockerSounds !== undefined ||
-    meta.lockerColors !== undefined ||
-    meta.lockerTrippySkins !== undefined ||
-    meta.soulImport !== undefined ||
-    meta.urnImport !== undefined ||
-    meta.lockerHero !== undefined
-  );
-}
-
 function metadataFor(entry: DmmAdoptionEntry): ModMetadata {
   return {
     modName: entry.modName,
@@ -356,9 +340,14 @@ export async function migrateDmmInstall(opts: DmmMigrationOptions): Promise<DmmM
   const allMetadata = loadMetadata();
   const managedSubmissionIds = new Set<number>();
   const managedHashes = new Set<string>();
-  for (const meta of Object.values(allMetadata)) {
+  // Unknown VPKs carry a hash too (startup backfills one for every file), but
+  // they are what this import exists to identify, so they are not "managed".
+  const unknownKeyByHash = new Map<string, string>();
+  for (const [metaKey, meta] of Object.entries(allMetadata)) {
     if (meta.gameBananaId !== undefined) managedSubmissionIds.add(meta.gameBananaId);
-    if (meta.sha256) managedHashes.add(meta.sha256.toLowerCase());
+    if (!meta.sha256) continue;
+    if (hasModIdentity(meta)) managedHashes.add(meta.sha256.toLowerCase());
+    else unknownKeyByHash.set(meta.sha256.toLowerCase(), metaKey);
   }
 
   const adoptableEntries: DmmAdoptionEntry[] = [];
@@ -431,6 +420,9 @@ export async function migrateDmmInstall(opts: DmmMigrationOptions): Promise<DmmM
         ? (await fs.readdir(disabledPath)).map((n) => n.toLowerCase())
         : []
     );
+    let pathByKey: Map<string, string> | null = null;
+    const installedPaths = async () =>
+      (pathByKey ??= new Map((await scanMods(opts.deadlockPath)).map((m) => [m.metaKey, m.path])));
 
     for (const entry of ordered) {
       // A DMM mod may own several VPKs; adopt each one, tagging all with the
@@ -474,7 +466,15 @@ export async function migrateDmmInstall(opts: DmmMigrationOptions): Promise<DmmM
         try {
           let destPath: string;
           await assertVpkSafety(src, { context: 'installation', name: entry.modName });
-          if (entry.enabled) {
+          // Grimoire may already list these exact bytes as an unknown mod in
+          // another file (DMM's live copy while this one sits in a profile
+          // folder, or the same mod dropped in by hand): identify that file
+          // rather than adding a second copy of the mod.
+          const twinKey = unknownKeyByHash.get(srcHash);
+          const twinPath = twinKey ? (await installedPaths()).get(twinKey) : undefined;
+          if (twinPath && resolve(twinPath) !== resolve(src)) {
+            destPath = twinPath;
+          } else if (entry.enabled) {
             if (mode === 'in-place' && isLiveEnabledSlot(src, addonRoots)) {
               // Already a live pakNN_dir.vpk slot Grimoire scans: adopt by
               // metadata only, no copy.
@@ -483,7 +483,7 @@ export async function migrateDmmInstall(opts: DmmMigrationOptions): Promise<DmmM
               // Skip anything Grimoire already manages (a prior import, or a
               // local/Locker VPK that happens to occupy this slot): re-tagging it
               // would hijack its identity. Only a truly unmanaged file is adopted.
-              if (existing && isGrimoireManaged(existing)) {
+              if (existing && hasModIdentity(existing)) {
                 fileSkips.push(`${vpkName} (already managed by Grimoire)`);
                 continue;
               }
@@ -503,7 +503,7 @@ export async function migrateDmmInstall(opts: DmmMigrationOptions): Promise<DmmM
             const existing = getModMetadata(metaKeyFor(destPath));
             // Don't re-tag a file Grimoire already manages (a prior import or a
             // Locker/local surface parked here): that would hijack its identity.
-            if (existing && isGrimoireManaged(existing)) {
+            if (existing && hasModIdentity(existing)) {
               fileSkips.push(`${vpkName} (already managed by Grimoire)`);
               continue;
             }
@@ -528,6 +528,7 @@ export async function migrateDmmInstall(opts: DmmMigrationOptions): Promise<DmmM
           removeModMetadata(metaKey);
           await setModMetadataWithHash(metaKey, meta, destPath);
           managedHashes.add(srcHash);
+          unknownKeyByHash.delete(srcHash);
           adoptedKeys.push(metaKey);
         } catch (err) {
           fileSkips.push(`${vpkName} (${err instanceof Error ? err.message : String(err)})`);
diff --git a/electron/main/services/metadata.ts b/electron/main/services/metadata.ts
index 10a1ae07..eb8f76c6 100644
--- a/electron/main/services/metadata.ts
+++ b/electron/main/services/metadata.ts
@@ -139,6 +139,32 @@ export interface ModMetadata {
 
 export type ModMetadataMap = Record<string, ModMetadata>;
 
+/**
+ * Whether a sidecar row records an identity: a GameBanana link, a name, a
+ * Grimoire-built VPK, or a choice the user made about the file. Startup gives
+ * every unknown VPK a row too (the sha256 backfill, the inferred hero and
+ * global type), so the mere presence of a row, a hash or a `lockerHero` does
+ * not mean Grimoire manages the file.
+ */
+export function hasModIdentity(meta: ModMetadata): boolean {
+    return (
+        meta.gameBananaId !== undefined ||
+        (typeof meta.modName === 'string' && meta.modName.trim().length > 0) ||
+        meta.lockerHeroSource === 'manual' ||
+        meta.merged !== undefined ||
+        meta.forgeInstall !== undefined ||
+        meta.lockerCosmetics !== undefined ||
+        meta.lockerSounds !== undefined ||
+        meta.lockerColors !== undefined ||
+        meta.lockerTrippySkins !== undefined ||
+        meta.soulImport !== undefined ||
+        meta.urnImport !== undefined ||
+        meta.soundSwap !== undefined ||
+        meta.localGroupId !== undefined ||
+        meta.priorityMod !== undefined
+    );
+}
+
 // In-memory cache of the parsed metadata.json. Without this, every enrichMod
 // call (one per installed mod) re-reads + re-parses the whole sidecar from
 // disk on the main thread; users with many mods see noticeable freezes on