If you look at my script I made, you'd notice that I was using variable 0x5000 to ensure the script only ran during the event duration. That, with conjunction of setting flags, create the effect of the Mankey event not happening again.
I explained how (more thoroughly) in my post. You should read the whole thing over again until you can understand it how it was done. I know you are still learning, can be hard to understand in one sitting. If this is the case you need to make an effort to learn some of the basic scripts, otherwise I will not help you with future problems. I mean, I literally gave you the script, and you're wondering how to fix a problem I already addressed...
I can't help you make your hack, but I can help you if you have questions about a particular problem. I suggest reading some of the scripting tutorials and the tutorials on how to use Advance map (if you're just starting out and have no idea how to proceed).