Second Stud Fee for Accidental Breeding?

Not sure what to do…my stud was away for 3 days to breed one female, with the agreement that my stud fee would either be pick of the litter or $1,000. The females owner called me yesterday to not only tell me that 9 puppies were born, but that her other female also had 9 puppies the same night! She believes that my stud got to her while they were all sleeping. My dilemma is that I understand that this was an unforeseen circumstance and the females owner is overwhelmed by the situation, but he did sire another litter that is still AKC eligible and both parents have had their testings done. So they’re not mutts or an incompatible pair (we crossed them 2 years ago). Is it unfair of me to ask my normal flat rate of $1,000 as the stud fee for the second litter on top of our original agreement for the first litter?

UPDATE/EDIT: We are going to do the DNA testing, but here’s dilemma #2. (This is her response to the second stud fee.)

“So I’ve been thinking about the Stud fee as well. I want to make sure you guys are taken care of. And as I’ve mentioned in the past, I think [my stud] is worth his weight in gold. The only reason I might want to see if you’re willing to negotiate for a lower fee would be because I’m looking at hiring a teenager nearby to help us clean up after them as soon as they get to a month old. It’s such a hard task in the winter time Because we can’t just spray things down. we have found in the past that they have to be cleaned up after, ideally, three times a day and twice the puppies means twice to poop. So let me know if you have any thoughts about that.”