I know this is a possibility on US carriers, but does BA offer the option to sell two seats to the same person. I am aware of the option of buying a middle seat in advance, but I am asking whether Mr.FlyingTurkey can sit next to Mr.FlyingTurkey and collect double avios/TP??

I'm sure theres some clause somewhere that prohibits it but considering other countries do it I was wondering why BA would say no.