I wouldn't do that if I were you. Pick one or the other kind and get two of those. If you got one of each kind and they interbreed, no one who is in the dart frog hobby will want to buy the offspring - there is a big anti-hybrid feeling in the hobby.

Also, keep in mind that two tinctorius of the same sex, no matter what race they are, will almost always fight. In the case of females, this is almost always to the death of one of them.