One could argue that this is a difference in style, especially considering that Moghedien believes herself more talented and skilled in Tel'aran'rhiod (see the encounter with Egwene in TFOH). I realize that it's quite possible Moghedien is just delusional. I'm just saying, I don't see any particular reason to assume it's Lanfear. What's the point of assuming that anyway? Any plot extrapolation you could make would be wildly circumstantial by nature. Moridin is more of a certainty, and the one who exhibits the best understanding of future events by a long shot, so that's slightly different.