In this episode its suggested that Paul & Jamie are close to the same age. In the Laugh in/Dream episode years later Paul says to Jamie "I keep forgetting how young you are". Paul Reiser is 7 yrs older than Helen Hunt.
Mad About You and Friends exist in the same New York universe. Ursula Buffay, Phoebe Buffay's twin, was moonlighting as a tour guide at the American Museum of Natural History at the same time Ross Geller would have been working there. It seems odd that he never mentioned a colleague who was the identical twin sister of one of his best friends.