Yeah, that's a distinct probability. Especially if they were using stuff that was just lying around. Alotta 63rd Jugs almost had a purple-ish cast to them. The one in this photo certainly seems to have a purple-ish look to it; although who knows what effects time has had on the original transparency and also what may have happened during the printing process for the book from which this image was scanned. As I usually say, there's way too many variables involved.
The 61st is said to have had a similar problem with paint supply, and many of their ships were reported to have been black and/or midnight blue and who knows what other colors. The fact that many P-47's of the 61st were not in the black/blue scheme at all seems to bear this out. Then again, perhaps it was personal preference on the part of the pilot or crew. Who knows for sure...
But I, for one, would go with the two blues. Perhaps adding a bit of red to the darker color. Too many photos I've seen indicate that both colors are, indeed, blue for me to do anything else.
Fade to Black...