I’m not too sure what you mean – every game will have its own name, so you can have multiple save states of each game. They wont overwrite eachother. These are the relevant lines
# State slots. With slot set to 0, save state name is *.state (or whatever defined on commandline).
# When slot is != 0, path will be $path%d, where %d is slot number.
# input_state_slot_increase = f7
# input_state_slot_decrease = f6
# When saving a savestate, save state index is automatically increased before
# it is saved.
# Also, when loading content, the index will be set to the highest existing index.
# There is no upper bound on the index.
# savestate_auto_index = false
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