In the crown of swords, Rand is fighting Samiael and they wind up in Shadar Logoth. They are attacking each other at some distance with verying degrees of accuaracy. They cant see each other. Sam brings down a lightning bolt or something, the ground gives way and Rand winds up hanging on with one hand. Somebody helps him out, somebody that rand almost recognizes but doesn't. Who could this be? I've got nothing.

Moridin, who is Ishamael/Ba'alzamon brought back and putinto a new, not-so-dead, body.

that was my first though but was put off be Rand thinking this guy was familiar. He has never seen the new Ish. But wait, I have heard it said that RJ over discibes the clothing of people so he can sometimes throw one of the chosen in without us noticeing it. Could it be that Ish, in his new body has been in one of the various throne room that Rand occupies?

Rand does not recognize Moridin in SL, Rand's POV says flat out that he has never seen him before.

Its also possible that Moridin's 'persona' or aura is so strong, and Rand / LTT have had so many dealings with Ba'alzamon and Ishy that he thinks he recognises him.

That's possible......