Cannot delete colors from document palette

Does anyone know why I am unable to delete colors from my document palette?  Years ago, I installed the Roland Versaworks custom color palette that includes a custom spot color used for contour cutting vinyl products (labeled "CutContour").  After opening some of my older files generated in earlier versions of CorelDraw, the "CutContour" color seems to "breed," resulting in multiple instances of the same color with an appended label (e.g. CutContour (7), CutContour (8), CutContour (9), etc.).  In one specific file, there are 41 replications of the same "CutContour" spot color in the document palette!  I can use the palette editor to delete all but 2 of the 41 iterations of the CutContour color.  Two of the CutContour colors in the document palette (CutContour (39) and CutContour (40)) simply will not delete.  When I try to delete these two colors, I am told they are "in use" and cannot be deleted.  I tried doing a find/replace of those two colors and it finds zero instances of either of these colors anywhere in the file.  Additionally, after I delete the other 39 iterations of the CutContour spot color from the document palette and subsequently save the document palette, as soon as I close and reopen that specific CorelDraw file, ALL 41 iterations of the CutContour spot color return again!!!  Please help!