Russ was actually played by David Schwimmer himself, using prosthetics and makeup to slightly alter his appearance.
Following their massive fallout over the infamous "Pros and Cons" list, Rachel attempts to get back into the dating game. Enter , a periodontist who is, for all intents and purposes, a carbon copy of Ross Geller. [S2E10] The One With Russ
The One With the Doppelgänger: A Deep Dive into S2E10 "The One With Russ" Russ was actually played by David Schwimmer himself,