t5Nitro,
Thank you for your post. We recommend great caution if you attempt to add a clownfish to a tank with an established clownfish. Should you decide to proceed with this, we recommend rearranging the decorations or live rock in order to force the fish to establish new territories. You could also take out the established clownfish, let the new clownfish adjust and then re-introduce the older clownfish. As far as sexing the two fish, it would be impossible to predict with certainty what sex each would be. If you do have two males, then one would definitely morph into a female to establish a pair. Should you need additional information, please contact us at 1-800-334-3699.
Cassie Z.
Tech Support
LiveAquaria