Gee I almost forgot, this actually happened to me.
I had a great offer from 1 of top 20 semi companies (DSP..) with big increase over what I was getting already so of course I was excited and accepted, but days before the move was set to happen..
Worst thing happened, somebody else came along that was desperate, really desparate, they doubled that offer and made it impossible for me to refuse both in stock, salary etc, I switched, the other company understood, they knew it was an exceptional counter offer so they let it go as one of those wierd things. 2x was not something they could do anything about.
Do I regret doing this, yes & no, 1st company is a rock solid company I would have done well at and they are still here and stronger. The company I went with had alot of potential upside (and it was way before the bubble started). The gig lasted along time, was an interesting ride and I learnt as much as I would have at the 1st company, maybe more. Well the bubble did eventually burst and they barely exist now, lots of stuff outside my control, but I can now do my own gig.
Would I recomend doing that again, in a booming economy that can be okay for seniors, but today I wouldn't do it and also youngen's shouldn't do it either as it really messes up your future options. Once you get into the mile high club, you won't be so welcome if everybody thinks you want 2x. If you want a long company career you will be in a salary tunnel that is fairly limited anyway. 20yrs exp is only worth 2x recent graduate unlike in other professions.
Do your homework on the company, did you like the people you met, if so it will probably work out, if not don't go there. If you get other offers, they will likely be very close in salary anyways.
regards
JJ