Curious why is so ? Maybe some networks will explain this "phenomen" when exact same offer performs badly than it was with higher payout. So somebody is cheating and shaving leads, am I right ?
If it's exactly the same page, then I'd lean with funny stuff going on. However if it's on another domain name, or something else is different (extra field) etc.
I've noticed also that on some offers the first page is the same, but the 2nd page has different pricing, different verbage, prechecked vs non checked.
You have to investigate if the offer matters.