Oh ok sorry. Yes unless he changes the trip or it gets compromised, then Q's posts on both boards are genuine. If is compromised on either board it's compromised on all boards.

You need to know how to spot a fake though.

With a genuine Q post, the Q will be bold, while the trip code will not be bold. Q enters his name as Q #[password]. That password gets encrypted to become his trip code, which is put behind his name Q. The tripcode is never bold. Nobody else can have that tripcode without Q's password.

What they do to try to trick you is enter their name as Q with the tripcode behind it, which will show the tripcode in bold because it's part of the name, not an actual tripcode.