I might be wrong about this but in general I have found that cases (not only gun but others as well) that have one or two combo locks are inferior to those that have a single keyed lock.
I don't know why, but Mexican and Hong Kong cases tha tfall apart quickly all seem to have the double-combo locks.
Sort of like real crappy double-sash windows have two closers - not one. I think it compensates for crummy construction and fit.
I have the all leather case from Galazan with a single keyed lock. It fell off. Literally the lock fell of the case one day. No abuse, hardly any use. Just fell off one day.