Not who you replied to, but I always assumed that she sort of knew about her second personality from previous occasions when this had happened. The terraformer with the god complex (whom i found the real star of this episode, LET THERE BE LIGHT!) tells sisko about it, so it is implied that she is even aware herself whom she mr. Hydes into to some degree. She may not have the memories, but should know about her second personality.
Since the age of streaming has made it very uncertain that shows are completed or even get a reasonable finale episode I prefer waiting until a series is complete before I start watching it. Nothing worse than getting invested in a show only to have it cancelled mid story arc. Also makes binge watching easier.