It's probably happened to everyone; Someone tells you they "saw someone that looked just like you" at a party or on the street. With 6 billion people on the planet, it's bound to happen. The great thing about TV is that stuff like this happens all the time: Long lost twins or random people that just happen to look like a once beloved character show up in town and usually are totally evil, take up with their dead/missing lookalike's significant other, or both.
The recent revelation that "All My Children"'s resident nosy caterer, Marissa, is really the long lost (fraternal) twin of poor, dead Babe got us thinking about the wonderful history of twins, lookalikes and clones (yes, really) that have populated our beloved shows over the years. Of course, Marissa and Babe look nothing alike (even considering Babe's first face). But, whatever, it's a jumping off point.