fix: dedup core extras on their real destination

tests/test_undeclared_dedup.py

@@ -0,0 +1,43 @@
+"""Same-named core files at two paths stay two files in standalone mode.
+
+find_undeclared_files keyed its dedup on standalone_path alone when the
+platform runs the core standalone, while the destination it then writes
+falls back on path. Batocera runs clk standalone, clk declares basic.rom
+under Acorn/ and Electron/ without a standalone_path, and the second was
+dropped from the pack.
+"""
+
+from __future__ import annotations
+
+import sys
+import unittest
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+sys.path.insert(0, str(REPO_ROOT / "scripts"))
+
+
+class StandaloneFallsBackOnPath(unittest.TestCase):
+    def test_both_paths_survive(self):
+        from verify import find_undeclared_files
+
+        profile = {
+            "emulator": "Clock Signal",
+            "type": "standalone + libretro",
+            "systems": ["acorn-electron"],
+            "files": [
+                {"name": "basic.rom", "path": "Acorn/basic.rom", "required": True},
+                {"name": "basic.rom", "path": "Electron/basic.rom", "required": True},
+            ],
+        }
+        config = {"cores": ["clk"], "standalone_cores": ["clk"], "systems": {}}
+        db = {"files": {}, "indexes": {}}
+        found = find_undeclared_files(config, "emulators", db, emu_profiles={"clk": profile})
+        self.assertEqual(
+            sorted(f["path"] for f in found if f["name"] == "basic.rom"),
+            ["Acorn/basic.rom", "Electron/basic.rom"],
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()