WELCOME sir !
Your double-show views are NORMAL. Here is why:
...quite often cockpits dedicated to an aircraft are few.
So, to rush into a FLYABLE version of a mod, the closest PIT available to the desirable cockpit is sometime used, kind of "in a franken way".
The pit fits into a PLANE-NOT-TO-BE-SEEN bubble, with the external plane being seen from the pit-pos at some distance, outside the empty air bubble.
Either the pit is small inside a big bubble: then external parts of the plane must be created/introduced to fill the gaps... ( inserts ).
( Here the main pit seems dedicated, with engines seen being cockpit parts; however the other positions-pits are imports from Ju-88 ).
...or the pit is large in a small bubble with no need to insert external parts, BUT...
.. as a result BOTH real external cockpit frames as well as the INTERNAL frames provided by the cockpit are seen at the same time.
To sum it up: plane is a mod, cockpit is a mod; both must be merged and matched into a perfect internal view of the outside world.
I hope that's make sense to you.
Sometime having a flyable is better then lacking the non existing perfectly exact suitable cockpit. ( i.e. AI only ).
PS: .. I remember having few problems to run UP3 after running DBW, and recall that a key important file must be pulled in or out USING the JSGME...
...been a long time since I used these so check it out in the JSGME options. [ ...edit; i.e.: #UP#_Enable_UP3.0 ]
Kind of very scarce on time right now, so I wont be able to chat much more.
Good luck!.