FAQ for
RoboCop (1987) More at IMDbPro »

We can only be certain that it was Emil that knew Robocop's true identity but it's possible that Emil may have told the rest of the gang later on. However, when Clarence fights Robocop in the final confrontation he doesn't acknowledge knowing who Robocop was.

However, during the final confrontation Clarence holds out his hands (as to be arrested) and Murphy shouts "im not arresting you anymore" which Clarence replies "wait a minute, you're taking this kinda personally ain't cha?". Which would suggest that he did know that Murphy was Robocop but then again they already encountered eachother at the cocaine factory so Clarence could have been referring to that incident.

RoboCop's unrated edition is probably one of the most infamous versions of its kind because director Paul Verhoeven had to cut his movie in order to get a R-rating. But with the possibilities of the growing home media market his real RoboCop cut got released that is far more violent than the old theatrical version. A detailed comparison between both cuts with pictures can be found here.