It seems like this daily is triggering twice with each ally that I play.  Not sure why.  Has anyone else noticed this?  It's a nice easy way to get some gold, but...

This happened to me tonight also. I noticed it triggered twice when I failed to get an ally. This first trigger was using the ally. The second trigger was the missed ally breaking apart.

If you discard an ally for an extra explore, don't take the explore and then hit the >> button the game asks you if you want to skip your explore or go back.  Going back let's you cancel the ally by moving it back to your hand, but it has already counted as being played for the challenge.  This can be repeated 25 times to complete the challenge in a single turn.