Can you find the same friendly monster more then once and gain the same benefits a second time?

Yes, I do believe you can. Iirc.

Actually, no you can't. Once you give them the gemstone they want, that's it, you'll never see 'em again.

But they might throw you a party if you find each one 100 times. And then you get new costumes for everyone and Aeris comes back to life if you use the save file in your FFVII game.

and then you get to play as Ozma if you guess his measurements right(the yan asks you that ? after you give him a diamond)

Actually, no you can't. Once you give them the gemstone they want, that's it, you'll never see 'em again.

But they might throw you a party if you find each one 100 times. And then you get new costumes for everyone and Aeris comes back to life if you use the save file in your FFVII game.

Also if you use this save file on the ps1 version of FF6, General Leo will wake up! (and you get the famous Lion Sword too!).

....and if you're the twelfth caller, you'll win two tickets to the monster truck extraveganza being held tonight at the Carson Fair Grounds. Featuring Big Daddy Don Bodine's truck: The Bohemiath. The twelfth caller wins on the station where the 70's survived... K-B-I-L-L-Y...