Antonia

Coins of Antonia are considered scarce.

The second coin is duble bigger than the fisrt

The second one has a different style than what we usually see. It reminds me of some of the Claudius issues from Spanish mints. I have not seen this in Antonia but I'm no expert so could well have missed it. If that is correct, the coin could be important to a specialist in branch mint issues. The coin has some surface bumps that I don't like so I'd suggest submitting that one for a certificate. The first has correct style but I suspect will be found to be light weight due to harsh cleaning or being an individual field find rather than part of a hoard. Such surfaces also can be perfectly genuine or applied to hide something so that one should be shown to a dealer with considerable experience in this period as well. My experience with first century coins is not strong enough to feel good saying whether a photo shows something good or bad but scarce coins of Julio-Claudians are popular targets among fakers so extra care is needed.

I know nothing about Spain and coin collecting. Is there a museum that is willing to help collectors? A trustworthy dealer in a town near you?

At that size and weight that would make it a Sestertius. A rare coin.