The act of performing coitus with identical twins, at the same time. Stemming from the German term, Doppelgänger. Similar to a Threeway, or a Threesome, the Doppel Gang-Bang captivates the participants imagninations, especially the male's.
"Dude, you should totally try to hit both of those twins at the same time. We can call it the Doppel Gang-Bang!"