Layer keeps showing - only want it visible once

Based on your description, it sounds like the trigger is on a layer that re-runs. After the associated T/F variable = True, every time that layer's timeline ends, the Match 1 Correct layer will show.

So you either need to change the "when" for the trigger. For example, show the layer based on the same "when" that changes the variable to True. 

Otherwise, you'd need to add some other condition(s) that would prevent the existing trigger from re-running.