I had 2 zodiac loaches at one point too, they got along fine sometimes but then the next minute they would be fighting. Seemed to fight for a long time circling each other and nipping fins etc. one of mine also had wounds on it ( red and round) they didnt seem bothered by the wounds, but i eventually got rid of tehm cause they were picking on the corys.
should make sure there not picking on your corys, but i guess if you got enough of them it shouldnt be much of a problem...