What was the one big, glaring, obvious addition to the '92 release? The unicorn. It was added to tie Gaff's origami to Deckard's daydreaming. The implication being, Gaff knew Deckard's thoughts, the same way Deckard knew about Rachael's spider memory, because they weren't real. That's an intentional counter to the ambiguity that was there before.
Not really. Most people have about 4-6 REM sleep stages per night, give or take. That's over 1800 dream cycles a year -- and each individual dream cycle will likely involve multiple different topics over the course of the dream. With that many chances, it's statistically inevitable that you'll occasionally dream about something one night and then encounter something similar in real life a day or two later. And a unicorn is a popular mythic archetype -- no doubt lots of people dream about them, and lots of people like creating artwork of them, and that means the odds of a coincidental convergence involving unicorn imagery are quite high. So the unicorn thing suggests that Deckard could be a replicant, but it's hardly unambiguous.
So maybe the point was to create the question in Deckard's mind of whether there was a chance that he could be a replicant. That is, it's not about removing ambiguity for the viewer, but about creating ambiguity for Deckard. The unicorn doesn't prove anything, but it could be enough to make him wonder.