I have some assemblies that all have legs on them so I save apart named leg when I create the assembly. These files are allsaved in separate directories when created.

Open any one assembly(1) at a time no problem. If one is open andyou open a second assembly(2) that has parts with the same name asassembly(1) it will open assembly(2) with assembly(1) legs, andeven change the references back to point to the directory of partsfor assembly(1)SolidworksAssemblies