Unpivot multiple columns but not duplicate rows

Hey guys,

Hopefully, you can help me with my question! Been trying for a few days now, and after a lot of frustration decided to see whether you guys can help me. I'm using Power Query (not BI) to transform data output from one system to an importable format for another system. However the structure of both files is not quite the same so that's where I need some help. 

In my original file I have two columns with comma separated values. Both of these columns need to be unpivoted/transposed but without creating duplicate rows. Because the test still remains the same however instead of aligned horizontally the staff and class need to be aligned vertically.

If my query works correctly it needs to look the following:

However after splitting the columns, unpivoting both of the columns it creates duplicates for each instance and looks the following (also tried to create two different queries and merge them but with the same effect):

(I already know how to create the null values in the other columns, the main problem is with the duplicates in the columns Staff/Class).

Hopefully you guys know the trick on how to solve this, or if it is not even possible how I get closest to my desired result.

If you need any more information, please let me know! Thanks a lot for your help...

Regards,

Niall