In your example, which solution is recognized by tests as valid, and which as invalid?

I think (I cannot remember exactly tho) that if the first pieces are equal, need to pick the solution where the second piece is wider, and if the second pieces are also equal then the solution where the third piece is wider, etc. So in your example, pieces 1 and 2 are identical, but piece 3 is wider in solution 1, and narrower in solution 2, which means you should pick the solution 1.

Does this match your observation?