For Years I have the same problem. Sometimes I have notes duplicates, which is my fault, however, is there any way, I can select only top notes for whole track, or merge them? 
I always have to record again,but like now, I played something really good and don't wanna record it again, but also don't want to get rid of notes one by one, there is too many.  
 
To clarify, in piano roll, I have same notes at the same time doubled, one under the other. 
 
Help 

Using the Event List editor view with your track selected, will show all of the MIDI events for that track, like note on, etc.
 
It should be obvious where you doubled up.  You can delete events one at a time in there.

There's also the UNDUPE.CAL CAL script you can run.
 

Bot answers amazing. 
However, Even log is okay, shows duplicates, but again, I can't just delete one by one as there is too many. 
CAL script, I wanted to use it, but I don't really understand it, or it  doesn't work. It doesn't find any duplicates.
What is window for time identity?  ( I think it;'s just time scale it looks to for duplicates).
 
CAL Script is the winner. Amazing, why I don't use it more often.  
The only issue with that is, id doesn't delete first duplicate but that's fine ;) 
Thank you