Board Thread:Spoilers!/@comment-2153169-20160901162450/@comment-24674051-20160913180007

Zelena spying on Emma and Hook, or even having spied on Regina, would not have told her one thing about Marian. Marian was "pretty vanilla" according to Regina, and she didn't remember her, and definitely did not know her name. I doubt Zelena is going to pick up on one prisoner out of all the prisoners that Regina had during her reign.

Personal head canon (since I dislike the "it was magic" reason). Emma and Hook did not know the name of the woman that they rescued, because at least Emma would have immediately picked up on "Marian", given the general common knowledge of the Robin Hood story in the LWM. So when Emma went to introduce the woman they brought back, her name was not known until ROBIN recognized her and blurted it out. Zelena is sharp, though, and rolled with it to her advantage.

I know that this may not completely fit with the story that Zelena told, but I think part of her story was revisionist history at work (head canon again). Zelena saw the woman being taken back as an opportunity to return to torment Regina more, but had absolutely no idea that the woman was Robin's long dead wife. That realization did not occur until Robin spoke. her revisionist history makes her look even more clever than she really was in that circumstance.