I've had the double upgrade once. I was booked into WT+ and at T-24 hours noticed I'd been upgraded to CW. Early enough that I could bag 15A for direct aisle access. Amazing. Got settled into my CW seat, enjoying the PDB, etc. and a woman and her son come over. The son sits in B and the woman is looking agitated. Goes to get the crew, complains loudly that someone (me) is in her seat and the crew tries to figure out what's going on. She goes on and on about how she can't sit separately from him. Crew comes over and checks my BP and notices that both of us have been assigned the same seat. From my seat I can see WT+ and know I'll be sent right back where I belong when the crew asks me to move seats. He comes back with a new BP and says 'we're going to move you to First. Don't worry, it's a better seat anyway!' My only F experience to date and it was incredible. The crew couldn't have been better and we got chatting about port (I'd recently been to Porto). On my way out a bottle of port was discreetly handed to me with a note saying it was for the 'inconvenience of having to move seats.' If I'd been gold at the time I'd have given a golden ticket, but alas, just a welldone was sent.