Is there any typical case where you want repeating tupels?
The case that comes first to my mind is when you're conscious about keeping down the size of the memory structures, so instead of having an array where each element is a small object with a couple of variables, you have the variables directly in the array in a specific order. I've written such code on several occasions.
Another specific case is to be able to fully describe the result of flatten operations.
A third interesting case is in parsers where you have arrays of some parsed info that are separated by less significant text, e.g. even numbered elements are objects representing parsed xml elements, and the odd numbered elements contain the text separating them. That would however require a variant where the array is allowed to end in the middle of a tuple.