Definitely a type of wall/rock lizard. Hard to see their markings, maybe ready to molt? I don't think they're poisonous, and I also don't think there even are any poisonous lizards. Regardless, should release them. The only reason not to would be if you definitely know that they're an invasive species. Some of these types of lizards are endangered too, so.

Poor Lil guys. There are no poisonous or dangerous lizards in Spain. Though there's always a chance of infection if you were bit hard enough to draw blood or get scratched. Let em go.