I used to have the same problem with my WTFs. One would eat all the crickets and didn't leave a lot for the other, so I eventually started feeding them individually in a separate container. I know RETFs are more fragile than WTFs though, so I'm not sure how feasible it is. It's also concerning that your frog's mannerisms have changed. Have you tried tempting the picky one with different insects? Maybe a change in food selection might help.