Problem with conversions from CPA

I have a site where I have ads from xtendmedia and a banner I made for an offer from adscendmedia. The ads from xtend are usually the same as my own banner (win a macbook pro).

The thing is that I have given a better placement to my own banner but it has a lower CTR and also a lower conversion per click ratio, which accounts up WAY less conversions per impression than xtend's ad, basically for what's usually the same offer, with xtend paying a lot less though for every conversion.

I may be missing somethng obvious here, but I can't seem to find what's wrong...any insight from someone?

Is it a "no scrub" offer from Adscend? If not, perhaps you're getting scrubbed.

Is it possible at such an extent? I have like 15 times less conversions per click than the other ones.

Yep if one offer is paying considerably less than the other, it sounds like one is scrubbed and one is no scrub. Also there are tons of advertisers doing free Apple offers (who will all convert differently), you don't say whether it's actually the exact same offer from the same advertiser or not.