HELP for distinguish auratus gender

[sopp2000]

Hi, I happened to get 2 Dendrobates auratus "Ancon Hill" from a breeder, who told me they are a couple.

I'm a newbe to PDF, and as I learnd from internet, their gender can be distinguished according to the pad size on their foreleg. So i took a photo when soaking them with their neighbor - Bumble Bee toad and Mantella betsileo.

But I was disappointed to find that both frog's pads on their foreleg are much bigger than on hind, which means they are both male?

Please help identify their genders~~Thank you