Actors with matching filenames don't spawn correctly

[CuriousMike56]

If you have multiple zips containing truck files with the same filenames (common with private mods) only one will spawn correctly. The first mod in the selector spawns OK, any duplicate filenames will fail to load all assets (meshes, materials etc):

16:52:08: Ogre::ItemIdentityException::ItemIdentityException: Cannot locate a resource group called '' in ResourceGroupManager::resourceExists at C:\Users\runneradmin\.conan2\p\b\ogre30c15d995aab6a\b\OgreMain\src\OgreResourceGroupManager.cpp (line 1566)
16:52:08: [RoR|Actor|Error] (Keyword: managedmaterials) Ogre::ItemIdentityException::ItemIdentityException: Cannot locate a resource group called '' in ResourceGroupManager::resourceExists at C:\Users\runneradmin\.conan2\p\b\ogre30c15d995aab6a\b\OgreMain\src\OgreResourceGroupManager.cpp (line 1566)
16:52:08: Ogre::ItemIdentityException::ItemIdentityException: Cannot find a group named  in ResourceGroupManager::isResourceGroupInitialised at C:\Users\runneradmin\.conan2\p\b\ogre30c15d995aab6a\b\OgreMain\src\OgreResourceGroupManager.cpp (line 1772)