In three separate instances, I've defeated a boss in an Ancient Hunt, the boss has dropped an item that intially appears unique but isn't.

The sound effect for a unique item drop plays, the orange beam of light can be seen emitting from the item and the orange beam can be seen on the minimap. The item name even read 'UNIQUE GILDED' before picking up. The only give away was that the item's name was incorrect and the image of the item was that of the regular variety.

It's worth noting that on at least two of three of these occasions I had 'Luck of the sea' equipped on my armour.