i have had this problem once,and 2 be honest mate,the only method that worked,was 2 kennel them away from each other,and wrk a routine around them,going by my experience mine would be not one bit dog agresive 2 wards any other dog but with each other ,they had pure hatred i hope am wrong but i dont think you will stop them wanting 2 get 2 grips with each other ,i even tryed muzziling them as last resort and let them go 2 it,thinking they would burn them selves out not a chance,they wernt going 2 respect each other 4 nothink, i would just keep them seperated saves a lot of unnesasery grief