combining arrays from different matrices does not seem to work (as I would expect)

In this stackoverflow question I try to exemplify the case. https://stackoverflow.com/questions/76632696/use-interfaces-for-scenario-analysis-in-brightway

If I create a combinatorial datapackage with one array changing values in the technosphere matrix (two possible values for one exchange) and other array changing values in the biosphere matrix (100 possible values for one exchange) I don't get the number of combinations that I would expect (200). However, if both arrays modify the same matrix (technosphere) I get the number of expected combinations.

@cmutel Perhaps this is the expected behaviour and this is not an issue but it looks strange to me

Start with the linked Stack Overflow example and reproduce the combinatorial datapackage case using one array for the technosphere matrix and one for the biosphere matrix. Compare it with the case where both arrays modify the technosphere matrix; the work is complete when the cross-matrix behavior is explained and the expected combination count of 200 is either supported or corrected.

Written by the indexing model from the issue text.