Is it a dupe? Urban Decay sin vs Stila kitten eyeshadow

I totally get why Stila Kitten and Urbay Decay Sin are popular eyeshadow shades - both are shimmery champagne nudes that light up the eye. What I don't get is why people online treat them like dupes. I have owned both for a long time and they serve totally different purposes in my collection.

Let's take a look at some swatches and the differences will make themselves clear.

Stila In The Know matte eyeshadow palette review & swatches

I love reviewing my well loved collection staples because I have spent a lot of time forming my opinion. I have owned the Stila In The Know eyeshadow palette for almost a year and still use it regularly. In The Know is all matte (and *real* mattes - no hint of shimmer in the pan) and contains 10 mostly neutral shades. The palette usually retails for $40, but I have seen it on sale for $20 at promotional events (like Ulta's 21 days of beauty) and in clearance sections. I bought mine at Sephora.

Stila In The Know matte eyeshadow palette

Note: This palette also comes with a Stila smudge stick eyeliner in halfmoon (dark grey). I used it a handful of times and disliked it. The eyeliner does smudge, but didn't set well on my eyes, resulting in transfer to my lower lashline. If you like the smudgy lived in eyeliner look, you might like this product, but I passed it along to a friend.