That's a really weird story.
Due to the high volume printing of pesos, some bills had defects in the past 18/24 months but here the serial numbers are very different.
Where do the bills they put in ATMs come from? They must be perfectly "ironed" (or whatever the verb) so don't they come from the casa central of the bank or the banco central?
If someone inside the bank was taking such risks, he would mix fake & authentic bills, but not place fake bills in a row (unless he wants to be discovered really quickly).
Could it be that the pizza delivery guy switched your two bills noticing you were oh-la-la, the pizzeria manager noticed they were fake and asked the delivery guy to come back to change them? If that's the case, at least one of those 3 bills is authentic.