Hello Paul,
Nice Madura blade! Thanks for showing more of your collection. I don't think anybody will complain - please keep them coming!
Keris with different pamor on each side are a bit more common on Java/Madura but also seen in keris Melayu. Since each pamor layer sits on the steel layer in the middle (san mai construction), it does not really matter during the forging whether the pamor is different. For complex pamor it might even be argued that it may be easier since you don't need to strive for keeping the pattern alike on both sides...
I hope Alan et al. will chime in the metaphysical pros and cons of having different pamor on each side. Of course, there are also the dwiwarna and triwarna blades with more than one pamor motif on any given side...
Regards,
Kai