I just heard a British announcer (well he had a British accent) pronounce quintuple as kwin TOO ple and I’ve always pronounced it as kwin TUH ple! Then come to find out that the AHD supports what I would have thought of as a British pronunciation. Do any USns pronounce it that way?
I frankly cannot recall ever having heard it any other way than the UH (as in duh!) sound and remain surprized that so many people go around mispronouncing it. I may have been a bit premature in my judgment.
While on the topic, does anybody pronounce illusory as ill-uss-ory instead of il-looz-ory? I remember hearing it spoken in that way by a coed whose looks made everything about her unimpeachable, and needless to say I never got a chance to query the source.