Or just certain positional elements?

I gave a really bad example, sorry Better example, for N=2 and T=int: [1 1 7 7 8 8 2 2 3 3]

don't think so, :and would be the way to do this, but it currently pushes you out of the sequence.

also noticed that function schemas expect a :cat, which is bad as one can't wrap it like [:and [:catn [:min :int] [:max :int]] [:fn (fn [min max] (< min max))]]

Could it be done with textual regular expressions using capture groups?

Something like (P)\1