it very hard to tell but listen to thier vocies

^I don't think you can precisely tell someone's age based on their voices.
For instance, I have a deeper voice than my older brother for some reason.

Guess I kind of assumed they were twins, and hence, had the same birthdate.
Flam's mustache, voice, and overall demeanor might make him seem slightly older to me, but there are really no reliable indicators one way or the other, so we can probably assume that they're twins. They do look quite similar, after all. ^~

its hard to tell if their twins or not

^ Just like it's hard to tell if one's older than the other or not.

I always thought they were twins...or the one with the mustache (forgot which one that was, I think he's Flam :P) is the older one