It is difficuilt to gauge how many players have '' Scored '' for both teams, as there have only been ten players who have played for both between the years of 1912 to 1997.
From records from what I can find, roughly out of the nine players that have made the switch only six players have scored for both teams, these being ;
From 1967 there has only been two players to play for both Manchester United and Liverpool, but not being sold directly. These two players were Peter Beardsley and Paul Ince, although Beardsley never scored a goal for Manchester United, only appearing in one game.
wes brown
Nicolas Anelka?
Jermaine Pennant, Scored an own goal for united as a Liverpool player and scored against united as a Liverpool player and won the Prem with THE ARSENAL but was born in Jamaica but has represented England.
Not at Liverpool he did not. See here (http://lfchistory.net/stats_own_goals_lfc_all.asp) list of all own goals scored by Liverpool players
No
paul ince Michael Owen
Tyler Durden
Liverpool
Tuncay Sanli
No player has hat trick against manchester united
I can think of Mark Hughes, scored for Manchester United against Chelsea in 1994 before moving to them a season later. Frank Stapleton scored for Arsenal against Manchester United in the 1979 Final and moved to United in 1981. Kevin Keeganscored in 1974 for Liverpool against Newcastle United, and went on to play for them in 1982. That's all i can think of
Michael Owen (two for Liverpool and one for Manchester United and Filippo Inzaghi (two for Juventus and one for Milan) are the only players to have scored three hat-tricks in the Champions League.