i have dr. doom, diabolic genius in my support row and on turn six i activate diplomatic immuntiy move him to my concealed row then play dr. doom, victor von doom.

can i do this?

yeah, you K.O the Diabolic Genius though.

The hidden area isn't considered separate from the visible area for the purposes of considering what the player controls. So the uniqueness rule still applies whether you are recruiting into the visible or hidden area while controlling the same named character in the visible or hidden area.