In my opinion, this "block" is actually two imperforate vertical pairs as the printed sheet was not vertically cut into two separate rolls as required.
This created horizontal pairs in error (SC 951a).
Additionally, the rows were not die cut either.
Canada's 2020 Unitrade catalogue values a imperfoarte pair at $225.00, so you have a minimum of $450.00 for the two pairs if sold separately and possibly much more leaving it as a block. A double production error.