When you index, you get every combination of indices. For example, arr(1,:) gives every combination of 1 in the first index and all the valid column numbers in the second index -- all of row 1. arr(1:2,:) would give every combination of either 1 or 2 for the first index and all the valid column numbers for the second index -- all of rows 1 and 2.
It is every combination -- not every unique combination. So arr([1 1],:) would give all of row 1 twice.
When you index arr([2 2], [3 3]), treat it like arr([A B], [C D]), where you get every combination arr(A,C), arr(B, C), arr(A,D), arr(B,D), even though some of those are the same as the others. With A and B both being 2 and C and D both being 3, you end up selecting arr(2,3) four times
