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You may have noticed that e.l.f. regularly makes products that look like more expensive products from other brands. They imitate the packaging, sometimes the name, and the basic type of product in an apparently attempt to attract people who want the higher-end item but aren't willing or able to spend the extra money for it. A good example is the
crazy cream blush I reviewed a while ago. Their strategy seems to work fairly well, because you'll often see e.l.f. products suggested as cheaper alternatives to similar-looking higher end cosmetics.
It's important to be aware, however, that often what e.l.f. is replicating is just the appearance of the product - that is, the packaging. They don't necessarily try to recreate the formula of the more expensive inspiration: the texture, pigmentation, scent, wear, finish, etc. That means that they are not necessarily a reliable source of real dupes. It's marketing, not SWFing.
e.l.f. Hypershine Gloss has been around forever and has been a favorite of mine for years. Though there are other brands that sell glosses in this click-brush type of packaging, Stila seems to me like the most likely reference point for e.l.f.'s version. But until just recently, I had never tried Stila's very popular Lip Glaze. I ordered several tubes of it in an attempt to find something to compare with the two e.l.f. glosses that I already had (and also because they were pretty, and so I bought a few that definitely weren't going to be comparable shades). In retrospect, I went overboard, because it turns out that I am not a huge fan of the Stila glosses.
Let that be a lesson to you (me) here: whether you're looking for an e.l.f. dupe or a dupe for an e.l.f. product, proceed with caution.
So to answer the question in the title before I go on to a more detailed comparison of these two products:
No. They are not dupes.