@@ -0,0 +1,15 @@
+---
+'@objectstack/metadata-protocol': patch
+---
+
+fix(metadata-protocol): `duplicatePackage` refuses a copied item whose renamed object reference meets a name the item already holds, instead of merging the two
+
+Clause-②: no
+
+`duplicatePackage` (ADR-0070 D4, the package duplicate route's method) renames every copied object into the target namespace and rewrites each reference to it where a property names an object: a string, an array entry, or a record key (a permission set's `objects`, a translation's `objects`).
+
+**FROM.** When a copied item also named the object the copy is about to be called, the renamed name landed on a name the item already held, and the copy merged the two with `failed: []`. A permission set holding `objects: { crm_customer: { allowRead: true }, crm2_customer: { allowRead: true, allowEdit: true, allowDelete: true } }`, duplicated into namespace `crm2`, was copied as `objects: { crm2_customer: { allowRead: true, allowEdit: true, allowDelete: true } }`: whichever entry came last was kept, so one grant was dropped, and here the copied object gained edit and delete the source set never granted on its own object. A translation's `objects` dropped one object's labels the same way. A hook whose `object` list held both names was copied as `['crm2_customer', 'crm2_customer']`, so its handler ran twice per event on the copied object.
+
+**TO.** Such an item is listed in `failed[]`, and nothing of it is written (no item row, no history entry). The entry names the item, the property, the name that moved and the name it met, and the source edit that clears it, for example: "Permission set 'crm_access' is not copied: its `objects` key 'crm_customer' follows the copied object to 'crm2_customer', a key it already holds there, which this copy does not rename. … Remove 'crm_customer' or 'crm2_customer' on the source, then duplicate again." Remove one of the two names on the source item, then duplicate again.
+
+**Unchanged.** An item with no such collision copies as before, its references following the copied objects. An entry the source item itself repeats is copied as stored. The source package is never modified.
@@ -26327,6 +26327,11 @@ export class ObjectStackProtocolImplementation implements
      * A copied permission set's field rules follow too: in `fields`, keyed
      * `<object>.<field>`, a key's object part takes the renamed object's name
      * and its field part is left as stored.
+     *
+     * A rename at a reference site that meets a name the item already holds
+     * there (a permission set's or a translation's `objects` key, a hook's
+     * `object` entry) is never merged: the item is refused in `failed[]`,
+     * naming both, before anything is written for it.
      */
     async duplicatePackage(request: {
         sourcePackageId: string;
@@ -26550,26 +26555,75 @@ export class ObjectStackProtocolImplementation implements
         // KEY (`permission.objects` is keyed by object name) or a `.name`. The
         // record key holds for prefixed names too: a copied permission set
         // otherwise kept `objects.<source object>`, a grant on the SOURCE.
+        //
+        // ⛔ REFUSED, NEVER MERGED: at a reference site, a renamed name can
+        // meet a name the item already holds there — the source also names
+        // the object the copy is about to be called (`dupdst_customer`, an
+        // object outside the package or not yet created) beside its own
+        // (`dupsrc_customer`). Two record KEYS that land on one key keep only
+        // the last entry: a permission set's `objects` dropped a grant (and
+        // the copied object could gain edit and delete its source never gave
+        // it), a translation's `objects` dropped a label. Two array ELEMENTS
+        // that land on one name bind it twice: a hook's handler ran twice per
+        // event on the copied object. So every such meeting is recorded in
+        // `collisions` — the path, the name that moved, the name it met — and
+        // the call site refuses the item in `failed[]` before anything is
+        // written for it. `renameMap` is one-to-one, so a meeting is always a
+        // renamed name and a name this copy does not rename; an element the
+        // source itself repeats is copied as stored.
         const objectReferenceProperties = new Set(
             (REFERENCE_SITES.byTarget.get('object') ?? []).map((site) => site.property),
         );
-        const deepRewrite = (v: any, atReference = false): any => {
+        type ReferenceCollision = { at: string; shape: 'key' | 'entry'; moved: string; met: string };
+        const deepRewrite = (v: any, collisions: ReferenceCollision[], atReference = false, at = ''): any => {
             if (typeof v === 'string') {
                 const whole = atReference ? renameMap.get(v) : undefined;
                 if (whole !== undefined) return whole;
                 return re ? v.replace(re, (m) => renameMap.get(m) ?? m) : v;
             }
-            if (Array.isArray(v)) return v.map((element) => deepRewrite(element, atReference));
+            if (Array.isArray(v)) {
+                const out = v.map((element, i) => deepRewrite(element, collisions, atReference, `${at}[${i}]`));
+                if (atReference) {
+                    const firstAt = new Map<string, number>();
+                    out.forEach((element, i) => {
+                        if (typeof element !== 'string') return;
+                        const j = firstAt.get(element);
+                        if (j === undefined) {
+                            firstAt.set(element, i);
+                        } else if (v[j] !== v[i]) {
+                            collisions.push({ at, shape: 'entry', moved: v[i] !== element ? v[i] : v[j], met: element });
+                        }
+                    });
+                }
+                return out;
+            }
             if (v && typeof v === 'object') {
                 const o: any = {};
+                const from = new Map<string, string>();
                 for (const [k, val] of Object.entries(v)) {
                     const key = atReference ? (renameMap.get(k) ?? k) : k;
-                    o[key] = deepRewrite(val, objectReferenceProperties.has(k) || (atReference && k === 'name'));
+                    const other = from.get(key);
+                    if (other !== undefined) {
+                        collisions.push({ at, shape: 'key', moved: key === k ? other : k, met: key });
+                    }
+                    from.set(key, k);
+                    o[key] = deepRewrite(
+                        val, collisions,
+                        objectReferenceProperties.has(k) || (atReference && k === 'name'),
+                        at ? `${at}.${k}` : k,
+                    );
                 }
                 return o;
             }
             return v;
         };
+        const describeCollision = (c: ReferenceCollision): string =>
+            `its \`${c.at}\` ${c.shape} '${c.moved}' follows the copied object to '${c.met}', `
+            + `${c.shape === 'key' ? 'a key' : 'an entry'} it already holds there, which this copy does not rename. `
+            + (c.shape === 'key'
+                ? 'A record keeps one entry per key, so the copy would drop one of the two. '
+                : `The copy would name '${c.met}' twice. `)
+            + `Remove '${c.moved}' or '${c.met}' on the source, then duplicate again.`;
         // ⭐ A COPIED PERMISSION SET'S FIELD RULES FOLLOW THE RENAMED OBJECTS.
         // `PermissionSetSchema.fields` is a record keyed `<entity_name>.<field_name>`
         // (`packages/spec/src/security/permission.zod.ts`), and the security
@@ -26738,7 +26792,21 @@ export class ObjectStackProtocolImplementation implements
                     continue;
                 }
             }
-            const rewritten = deepRewrite(item);
+            const collisions: ReferenceCollision[] = [];
+            const rewritten = deepRewrite(item, collisions);
+            if (collisions.length > 0) {
+                const noun = singular === 'permission'
+                    ? 'Permission set'
+                    : `${singular.charAt(0).toUpperCase()}${singular.slice(1)}`;
+                const more = collisions.length - 1;
+                failed.push({
+                    type: row.type,
+                    name: row.name,
+                    error: `${noun} '${row.name}' is not copied: ${describeCollision(collisions[0]!)}`
+                        + (more > 0 ? ` It has ${more} more such collision${more === 1 ? '' : 's'}.` : ''),
+                });
+                continue;
+            }
             if (rewritten && typeof rewritten === 'object' && !Array.isArray(rewritten)) {
                 rewritten.name = newName;
                 // [ADR-0086 D3] A permission set that declares its SOURCE