I do as David suggests. VE7CC's Cluster software v.3 software (but not v. 2) allows you to combined multiple spot feeds. (if you download the latest v.2 software, it has a button enabling you to update to the v. 3 software)
I don't think you want two feeds. If you get a single feed with all spots, N1MM will take care of presenting the 40m spots in the 40m bandmap, and the 20m spots in the 20m bandmap.
(I had the same trouble as you with Wintelnetx.)