Hi Janbo, Merry Xmas to you.
Yep this is a bug!
When an object mesh is drawn and the shadow mapping mode is set to 3 then texture stages 4,5,6,7 are all filled with a shadow map even if the object is set to NOT receive shadows. The shadow maps are not needed if the object itself isn't set to receive shadows so this is wrong.
I've changed the object code and added a check in C to see if the object is set to receive shadows and corrected it so you can use all the stages if wanted. I've attached an example project which uses stage 6 even though shadowmode 3 is enabled and with the extra code it works ok on my machine. Id suggest we add this as a bug to github so Paul can make the changes (its just 2 lines of code so is an easy change)