this isn't the article, but it's close.
1. When The Man in Black rescues Teddy by saving him with freshly murdered Lawrence's blood, he discusses what the hosts used to be like when he first came to the park 30 some years ago, saying that now they are flesh and blood. When William arrives at the park, the hosts are flesh and blood and are NOT prototypes as they would have been 30 years prior.
2. William clearly cares for Dolores in his storyline, he cares so much that he leaves his brother-in-law Logan behind in Pariah to be maimed by angry hosts to instead run away with Dolores. If he cares that much for her, why would he later repeatedly torture and rape her as The Man In Black?
3. This was the first time we saw William "break bad" - which some people thought was a pre-curser to becoming inherently evil like the Man In Black. However, William was instigated heavily by Logan and only reacted to him by pushing him up against a wall. He did not change how he treated the rest of the hosts. He continues to treat the hosts like real people and with respect, unlike most visitors to the park.
4. In an earlier episode, Stubbs mentions how far Dolores has traveled from Sweetwater with William around the same time that he also approved the pyrotechnics request from the Man in Black. We believe that Stubbs is in fact a human and not a host.
5. Finally, in the latest promo for what's to come in the weeks ahead, we see Dolores comes face-to-face with the Man in Black, wearing the new cowboy clothes she had on while she was with William as opposed to the dainty blue dress she usually wears in her normal, boring little loop.
Remember we pointed out that Dolores changing her clothes was symbolic for her awakening into the "person" she is meant to be?
All of the above, of course, does not negate the fact that Westworld is not telling a linear story, which is common for both of the showrunners. There could be two different storylines, because we just can't seem to ignore the different logos.
However both showrunners Joy and Nolan have said that they leave details as ambigious as possible to keep viewers guessing, but also that every details will eventually make sense. They may be leading us to believe that William and the Man In Black are the same person, only to shock us with an unforseen twist that proves they are not.