The back of the stamp is the interesting part. On the lower right corner we can see the Tawao cancellation coming through. However, there is evidence of two other cancellations in violet. The large one in the middle has the mirror image of the letters Kudat and the month of Au(gust). It has a double ring and is probably a fiscal Kudat BNBC or the unclassified Kudat BNB postmark.
The marking at the top left hand corner is part of a small double ring marking with large letters of N.B which would be compatible with a Kudat BNBC fiscal cancellation.
My conclusions are this is a wholly fiscal used stamp which has been washed at least once and reused. It was initially used at Kudat and then later at Tawau. The crayon cancel served as a stop to this illegal practice.
A real pity as the unwashed stamp with a good Kudat BNBC hand stamp would have been more desirable and valuable. Still, it is an interesting story.