Which is the 'real' Liberator has been discussed by many people for some years, and it does seem that original parts are now in both. Published drawings by Martin claim that the front hull (from the solar panels forwards), plus 2 weapon pods/arms, plus all three brass weapon pod antenna are originals on his - but that can't be completely true because the hull area he mentions is at least half original on Mat's, which is even proved by a photo published by Martin!
The talk of parts being split between the two gentlemen does not make much sense to me and don't understand why it would happen. While we saw the model 'destroyed' in the final season 3 episode in truth only the one arm was broken off. The model was then glued back together again and displayed in complete (if rather poor, but better than it is now) form at later public events during the 80s, photographs of which have appeared on the internet. Then it appears to have been borrowed off Mat and disassembled to produce the model kit, which Mat explains on the B7 dvds as he sits holding the hull parts that have been returned to him.
(Of course one question is did Mat get all the original parts back at this time? - or some fake bits?)
What puzzles me is that Martin talks on his website about how over the years he had 'collected 2/3rds of the original parts from various sources'. This sounds ok if you believe that it had been blown up in the show, but as it was complete and being displayed then it makes no sense at all. Why would the model have been broken up into bits and then kept by different people.
Its all very strange and I guess the only way of finding the truth now is to dis-assemble both models - which ain't going to happen. But at the moment having seen Mat's several times I would say that his is the more original.
It's like a broom. One of them got the head, the other the handle. They then built and added the missing head/handle and now both claim to have the original broom.