So is Katia Ivor's ex-wife, or not?

I'm not sure how she showed up, when she was already dead. I thought she had a twin sister maybe, but then she would have heard of Ivar more directly.

If she's not Ivar's dead ex-wife, or her twin, then Oleg somehow knew who Ivar's wife was, and found a doppelganger. Doesn't seem likely.

Maybe Ivar is just feeling guilty and imagining she looks identical.