I've researched a lot and haven't found any answers. This caseback is marked "beta". What does it mean?

 

Can you provide information on the watch itself. Pictures of dial and movement are essential.

 

Sorry about that. I cropped a little too much on my screenshot tool.

 

A normal caseback should look like this from what I found. Is the original one I posted a service replacement caseback or some kind of reproduction?

 

I’m guessing it’s a service replacement where the reference number was hand stamped on a “blank” Omega case back by the watchmaker before it’s return. But then I know nothing about these Mark IVs.

 

My best guess is they made generic casebacks in portugal to circumvent importation and duties, hence the missing "Fab Suisse/Swiss made" on the caseback.