Interesting pricing on RJ

Looking at February 2013, LHR-AMM is GBP 1,933.
However, of the same dates (with the same LHR-AMM flights) LHR-AMM-KUL is GBP 1,896. It is cheaper with despite through an extra 10,000 mile round trip via BKK (technical stop) and KUL detour.

LHR-AMM-HKG is cheaper at GBP 1,871 desire an extra 10,600 round trip detour,

Appreciate the comments about discounted fare to offset the pain of a mid-flight stop to these destinations