If your going to copy the base, correlate a better system for the files.
In the data file, make files of steamid64's, and within the file, each player can save their own base in that file under their own steamid64.

I will add a better save management for players in future, thank you for your suggestion. I may use API and make separate plugins like Copy Paste For Players or Copy Paste Playerified :D or idk Copy Paste Limits (because players will have limits - simple!).

Thank you for the response. :)