You don't need to do anything else...
If aplication with code:
Then when P1 run application data.ini will be look like this:
Start of frame -> save file data.ini to application directory where file data.ini store for example name od player
But When P2 run it then he change data.ini to:
however if you want avoid data conflicts you must store all player data in different files:
Start of frame -> save file "player_name".ini to application directory