Unique Helmet/Glove/Boot enchants from Metamorphs? (hard coded RNG block?)

Over 1000 meta morphs and over a hundred boot/helmet/glove enchants and none of the drops with an enchant were unique. At this point I’m thinking the devs hard coded the possibility of a unique item dropping with a guaranteed enchant. So one question I’d want to bring up is why would the devs feel like it is necessary to hard code an RNG block?

Edit: additionally, rare items need a wisdom scroll to ID, so it can’t be because of the wisdom scroll

Would kinda suck getting a nice helm enchant on a common unique. Can always spam chance orbs if it's the same base of something you want.