I ran into the problem before. I still cant get it to function right. basically what he want is the game to make only one sprite when overlapping another sprite. And if im right he want to despawn the sprite when hes not overlapping it in theory it should work but contruct two engine just repeat it because of the condition it doesnt know it need to spawn one.
Id suggest that you do something like if overlapping spawn the sprite then change the condition in the action such as a variable to something else and when not overlapping change the variable back to the original variable
This way you can pretty much can control a overlapping condition and to prevent it from firing more then once. and once you step off you are just changing the variable so that when you overlap again all condition are met again.
Id done this so many time just for this effect. Id really wish there was a way to mark an event block to run once never again even if the condition was met again. (trigger once while true does not alway work) Cause id hate to use group just for a single event every time just for those event