[mykeliu]

I've heard "quintuple" both ways so after reading your comment, I still don't know how you specifically pronounce "tuple" :P

[nostrademons]

I've also heard "quintuple" pronounced "quin-TUH-ple" when used as a verb and "quin-TOO-ple" when used as a noun or adjective, so there's a part-of-speech distinction as well...