I did a quick comparison of TDI and FB because they seemed similar in my head. I don't typically like dupes because I feel dumb for wasting money that could've been used on a unique color. Occasionally, though, I like a color so much that I don't mind having a dupe as a backup. Anyway, they're not dupes. FB's duochrome shimmer is much more obvious and than TDI. I don't prefer one over the other, and they're definitely different enough to own both.