I don't have lots of them - yet! - but my SIL is a stay at home mom and babysits my sister's daughter. SIL finds them both a handful (the girls are 15 weeks apart) and since the girls love having me around, the four of us go shopping.
I have looked like my father's sister since the day I was born, and now my brother's daughter looks just like me. The two girls could pass as twins, and when people see us when we're out and about, they will say to me your twins look just like you! and my SIL is standing right there. Thankfully she's got a sense of humor about the situation and is adamant that baby #2 will look like her side of the family!