I hate to say it but I think the new addition is also male but this time an orange flash possible cross with a double red. Again, if you look at the dorsal fin (at the top) you can make out that the front prongs are elongated. The behaviour you're describing is actually territorial agression me thinks
If you compare the first pic of the first fish with the new addition you'll see the similarities re elongated dorsal fins as he/she matures it may become more apparent. How's big your tank? You will need 2/3 females for each male and clearly definned territories (minimum of two) in the tank coz they will fight to the death during spawning.
Good luck

If you compare the first pic of the first fish with the new addition you'll see the similarities re elongated dorsal fins as he/she matures it may become more apparent. How's big your tank? You will need 2/3 females for each male and clearly definned territories (minimum of two) in the tank coz they will fight to the death during spawning.
Good luck