@James Rye
 
Note Fluttershy and Rarity’s reaction though.
 

 
The makers knew the scene was going to look disturbing. And so they had these two express that reaction.

@Trickquestion
 
I don´t think a magical one-trick clone pony counts as a living thing at all. Else somepony would have protested.  
They never had a life, they just copied one part of Pinkie´s behaviour, even the first one only copied Pinkie and did so quite badly, never remembering “her” friends names, panicing like Twilight Sparkle before a test and then copying herself!  
In other words all Twi did was dispelling the cloning spell of a clone and said clone is responsible for making Pinkie a very sad pony and they were all egoistical for their own fun hopping and destroying psychos, not listening to reason and not taking anything seriously unlike the real Pinkie who does (sometimes) know a line where fun is fun and where fun isn´t appreciated.
 
So yeah, tl;dr: Shut it.

Ah yes, overheating horn. A common side effect of MURDERING DOZENS OF NEWBORNS IN A SHORT TIME PERIOD!