Short answer: Don't mix breeds

Long answer: You shouldn't mix species of amphibians and/or reptiles because of a couple of reasons.

1.) All amphibians produce toxins that are harmful to other amphibians, ALL do, not jsut the well known ones, it may not be as stong as others, but it is really unhealthy to keep more than one species together, because they slowly kill each other.

2.) Care/Environment. Most frogs need different care and/or enclosures. ie: you can't keep a tree frog with a terrestrial toad.

3.) Depending on the species, some may assert dominance over others, which is very very stressful to both frogs.