Micro AIs: prevent potential conflicts of stored data

It’s theoretically possible that different Micro AIs’ evaluation
functions store information in the same variable within self.data.
This would only happen if the CAs have the same score and while this
should generally be avoided when setting up a scenario, it is better to
ensure that it cannot cause conflicts (not in the stored data at least,
the MAIs might still interfere with each other in other respects).