500 rounds 1 "Doubled"

Ok, I was working on shooting another 200 rounds this afternoon, which would bring the total round count on my CA C93 up to 500, with Monarch steel cased 223; great ammo by the way, no FTF issues like I had with various other brand ammo the first 300 rounds, and the cheapest I've found.

At around the 180-190 round mark of the afternoon I had an instance of "one trigger squeeze 2 rounds fired" or "doubled". Now, I was doing some rapid fire leading right up to this incident where as before I was shooting and very diligently reacquiring target. My buddy says that because it's still early in the breaking in process that it's hard to really nail it down and that this could have been a bump fire where the trigger group hasn't fully settled and the action cycled and the trigger reset before I took my finger off of it.

What do the wiser than I say?