It's so weird that this forum has a sizeable contingent of linguistics enthusiasts as well as the predictable map nerds.
I think there is a certain degree of crossover appeal.
My dictionary lists "backup" as having a secondary stress on the second syllable, which it does not for "ketchup".
Yes, that's immediately obvious to my ear. (Though German speakers
would put a similar secondary stress on the second syllable of ketchup.) What's less obvious is that that makes the sound in "ketchup" not an [ʌ].
(deeks around)
Ah, indeed wiktionary offers [ʌ] and [ə] as both valid for ketchup. [ə] basically is just what a lot of vowel sounds collapse to when they're utterly devoid of stress.