Yes. There's an abattoir near me where I have heard a couple of reports of people not getting their own meat back. With coloured pigs you can usually tell as you can still see traces of the black hair. Don't know if the ginger of a Tamworth can be distinguished from more common white pigs?
There's also another abattoir that I use where it is known that you don't get all your meat back. I certainly know that I always get less back than I expect, but don't know enough about the carcass to know what's missing. However - they are still my butcher of choice because they are a quarter the price of the first mentioned, they are lovely people to deal with, and the meat comes back all bagged up.