I have a couple of doors which join various bits of extensions. as the walls are double skinned they are very deep openings and the door is on one side leaving the other side looking a bit odd. is there any easy way to move the door into the centre and put a frame on both sides or would that interfere with the hinges?

It’s only going to open 80 something degrees and then bash into the wall/door stop which knocks off even more aperture? You’ll need narrower doors for the new frame? Sounds like max hassle for minimal benefit.
Pictures would be handy.

You’ve obviously not lived in a former but and ben.

It’ll look weirder centralised

I’ve just installed a double door frame into an existing 10″ aperture. Unless you have those swing both ways hinges like in a restaurant kitchen it’s best to have the frame flush to one room (so the doors can open all the way back) and leave a large reveal the other side. If you look at all the doors in a house they’re like this. Another reason is that you’re just screwing into fresh air (topical Damien Green reference) in the middle of a cavity wall.