Chimaeras in animals that have large litters are probably more common than acknowledged, as Richard points out, you would not notice if it wasn't an albino/normal mosaic.
There's not much anyone can say about this one without more photos from more angles. If it was my snake I'd be doing a full photographic survey (not easy when they are wriggling). Ultimately they only certain way to identify a mosaic is a DNA analysis of the different tissues.