They want to divide the racially aware right from the more kosher right.
Woke is now generally understood to mean "cares about racial oppression". The term woke is also seen negatively (whiney). The term dark has the obvious edgy or dangerous connotation.
Dark Woke, as a label for the far right, is supposed to make you think racially aware Whites are cringe and lame, because they care about race. Like a dark (evil) version of the cringe far left, who care about race. If neocons, civic nationalists, boomers, centrists, and non-woke democrats organically latch onto and propogate this term, then they will have succeeded in pushing racial awareness (for Whites) outside the Overton window.
Dark MAGA is similar, but tries to tarnish and damage the MAGA label. If this label caught on they would demand MAGA purge the "dark" racist group of MAGA. Or, they would claim all MAGA is dark and MAGA should be destroyed and "real Republicans" should take back control of the party.