Is it ok to wear wristband on both wrists or is it weird?

Strange question... But i don't understand your logic surely you're only conforming to conventional ways of wearing these fashionable write bands by wearing both on one arm.

Be different go crazy put one on each arm!

Hope this helps :)

Sometimes I wear a bracelet on each wrist & a watch on one of the wrists. Some people wear several bracelets on each wrist, particularly if they're bangles During the winter season, you may want to still be able to get your coat or cardigan sweater on & off as needed. Then, too, you should be able to get any of them off the right wrist easily in case you want to do any desk work & they're in the way.

wear them both on the same wrist. it'll show the contrast between the wristbands

No.