I have housed a couple together that I assume were male and female because their size difference, which was almost exactly what you have indicated in your original post. They were fine together. Now, I also keep mine very well fed. Some might say that I slightly overfeed (no health problems... I just get differing opinions as to what is "overfeeding" and what is ideal). I have always heard that a frog (and esp a White's) will eat anything that will fit in its mouth. Having said that, I think if they have a more appealing food source like bugs they aren't as likely to resort to frog-icide. Disclaimer: That is just what I've experienced with mine and I can't speak for anyone else's frogs. Likewise, make sure you have enough room in your enclosure for the pair of them. I'm would assume if they feel stressed or territorial, they would be more likely to move in on each other. I would allow roughly 20 gallons *per frog*. That's just me. I think the generally accepted size is 2 or 3 in a 30 or 35 gallon tank, but that seems cramped to me. I tend to err on the side of spacious. Just my thoughts