Reroll aces broken?

Umm I tried to roll 6 sets of 4, 1d6s and reroll aces. Instead of rerolling aces it just rerolled 6s a second time and added it. So it broke pretty good. I had deleted it because I wanted to link the page but is anyone else getting broken rerolls?

Ah, that may be a variant of reroll aces.

I know it from Deadlands Classic where in if you roll the maximum number on a dice, you get an extra dice. Is that not what you're thinking of?