Board Thread:Naruto Discussions/@comment-25011101-20140607173835/@comment-3306440-20140607180614

Yes. In fact Guy is able to open all of the gates (especially the Gate of Death) :)

This ability is only unique to Lee, Guy and Maito Dai, since it's a forbidden technique. :)

TO answer your question, Kakashi wasn't copying Lee's jutsu if I remember correctly. Sasuke was the one who copied Lee's jutsu. :)