Attached a screenshot. You can see two pets in the pregnant status and 19 "born" pets total. This happened after recently getting Soaring Firelight from a pet trade.

Thanks for reporting.

It's not a bug. This means only that you had free stable place when made a bid and then another pet was added to this place. We don't have hard limits for such cases because it can end in losing a pet (if we choose to discard a newborn) or an auction which has ended without results though there are were bids (if we choose the pet from from auctions and won't process the auction results).

I see, thanks for responding! It's definitely an interesting game design choice as to what you should do in these situations.