Yes, this is a bug in Java and C++ (artf1344 and
artf1345) Thanks for finding it.
The result is that some channels for slot 2 conflict with channels in slot 1:
2,1 X 1,3
2,2 X 1,4
2,3 X 1,5
2,4 X 1,6
2,5 X 1,7
2,6 X 1,8
If you can deal with 10 or less channels then you can work around these conflicts.