I would think most people don't open the consoles. To me there is a very easy way to tell. When you first get a console and open it. It will almost have a crack sound as you bust open those 30yrs old seats the screws are so snug in.
If it's recently been opened it won't do that.
Also, the duo-rs are very similar. There is one with a fuse and one without. I don't really follow any numbers I just know the physical difference. The one without the fuse also has less caps in it, along the row of caps just behind hucard slot.
This is the board I typically see in duo-rx systems. Ones with the fuse are in the duo-r.
I doubt many sellers are opening them and swapping components just to do it. But I suppose it could happen.