This is how I recall it : (The movie that is... I'm old but not that old!) :
All the slaves, including the real Sparticus, were hung on crosses ... the "I am Sparticus" thing was so the Romans would never be sure whether or not they had actually gotten Sparticus!

Then there is the old joke about the Roman Procurator leading a column of Romans - all driving chariot - along a road lined with men hanging from crosses. The Procurator stops and calls to one ofthe soldiers and tells him, "That man hanging on the cross over there is singing. Go find out what he is singing."
A few minutes later the soldier came back.
Procurator : "well?"
Soldier: "I Love A Parade."
Last line of the joke should be sung, of course!