Doubling up twice would decrease your standard deviation. If you come across this situation many times. I guess I still don't prefer one to the other for that reason. I see it as you're going all the way to 30k and it's a 25% chance. I go for the quadruple up and save the suspense. I could just imagine that damn "Who wants to be a millionaire" music and those lights as I was going for the second double up. Then I pick red and it's a SPADE! Wah wah waaahh. Whammies start running around and take all my cash. I'll take the quadruple up. Much easier to deal with the loss of $5k instead of $10k since just winning $5k is not an option.

Related Interesting Problem:
Is the Monte Hall Question already posted here? The one with the three doors (2 donkeys 1 car) and you pick Door 1 hoping there's a $30k car behind it(assumption: you don't want the donkey). He shows you door #2 with a donkey behind it, he then asks do you want to switch to door #3? Well do ya?