I was going through my collection a while back and I noticed I had two colors that looked the same. I don't purposely buy dupes really or anything that looks close to a polish I already have. The two that look similar are Orly Rococo A Go-Go and Zoya Jem. These are so close to being dupes of each other it hurts! The only differences I can tell are that Rococo A Go-Go has slightly bigger shimmer/glitter and is only a tiny bit darker than Jem. Jem is a little more red/pink toned. I prefer Zoya's formula since it seems to be a bit better to work with. Both formulas are good though.
Honestly, they look identical in person, so if you have one you really don't need the other (unless you really want it).
This is 3 coats of each polish with flash.