www.dl2rum.de

As usual I am a little confused!

Under the DXCC panel on the Main Log window I understand what "Mrthn CQ" is but I don't know what "Mrthn DX" is.

For example I am looking at a CE9 which I worked in July and it correctly shows it as Green for "Mrthn CQ" but Red for "Mrthn DX".

What am I missing?

When it is the same DXCC it should be shown in green. You should provide a screen shot with the QSO and DXCC visible.
Do you use the latest RUMlog version? There was a bug in an earlier version, but I can't remember exactly what the result was.