There are 3 venues (Sportpaleis, Lotto Arena and Vorst Nationaal) where one physical block has 2 numerical blocks, e.g. block 118/119. The numbering of the seats runs from seat 1 to 8 in block 118, and then from 8 to 1 in block 119.
Therefore, in the middle you will find two chairs with the same (chair) number, but in a different block. However, not all blocks contain the same number of seats, so other combinations than 8-8 are also possible.