Basically you interpret stuff like the name Ba'alzamon or the poistion of the Nae'blis in a clumsy way that it fits with your idea, though the more obvious interpretations are at least as likely. At the same time you ignore what is indicated in the PoV of SH and Moridin (contrary to Luc's/Isam's PoV, which immediately makes clear that both are one being) or what RJ/BS said, which implies that we have two separate characters, and believe those things were only said to fool us.

All in all, it's most unlikely that Moridin and SH are linked into a being like Slayer, and there is no real convincing evidence to support it, IMO.