No, the save files in this mod are not separate, if I remember correctly. However, if you want to do that in your own mod, then select "General info" in Undertale Mod Tool, and change the "Name" field.
you can use Undertale Mod Tool to decompile it. there’s also the source code at https://github.com/apia46/IWannaLockpick but you need GameMaker Studio 1.4 to use it