If I signed up for a site under my name but used my dad's credit card for an offer (same last name, address, just different first name) will I still get credit for the offer?
You should, my debit card has my mom's name on it but I've used it for offers plenty of times and still gotten credit for it.
so have i. Chances are you will get credit.
I'm pretty sure that the freebie sites don't cross-check CC info. You don't give your CC to Freepay and AFAIK the offer sponsors don't report CC info back to Freepay (or any other site). IIRC Jake or some other rep has confirmed this in the past.
However you have to complete the liofferli in your name. As long as the offer vendor is cool with you using a CC with a different name than what you signed up with, you should get credit.