Well we don't want to literally kill each  other. The life expectancy of Menesheviks under Lenin and my old compatriot Feliks wasn't too good.  Roza and Karl didn't live that long under Ebert and co.  On the other hand if you're saying pre WWI, then yes. The divide between the Bernstein types and the Luksemburg ones or between the PPS and the SDKPiL was pretty ugly in Germany and Poland respectively. (Just to name the two Roza was directly involved in.)