I've been working on a song I wrote. I wrote the drums from a map on a midi track grid in the piano view. I came back into the midi track yesterday to make some changes and it seems like all my map notations randomly duplicated throughout the song. Two and three layers in some places and offset. It's a complete mess. Does anyone know why this happened and is there any way I can reverse it? I don't want to have to re-write it because it was very complex and time-consuming. Thanks for any help in advance.

My guess is your causing a loop as suggested in the other thread. 
The offset is caused by your  MIDI latency. 
Check your input echo setting. 
You will not be able to use the CAL script as it will only remove notes duplicated in the exact same location. It might remove most. 
As you work- always stop every 15-30 minutes and back up your data. 
You can automate this function. 
Also use "save as" to prevent destructive saves.   
User error is always involved when things go bad.