This kind of leaves out the biggest question imo which is that of quality.
Usually, dupe's sacrifice quality for price. The fact that a market exists for this at all indicates a strong consumer acceptance of lower quality items.
I do wonder, if the "premium" option were to never exist, would these "dupes" even exist in the first place as they seem to enjoy an "implied" quality that the premium option pays for, whilst cannibalizing sales.