It is possible that a pseudobulb may have lost one or both foliar buds sometime throughout its life.
Perhaps it was due to physical trauma (watch those pruner blades!) or insect/pathogen infestation.
I think this is why the dormant eyes stay tucked into the pseudobulb as tightly as they can and only activate and swell the moment they are needed.
They try to stay hidden so that they are protected from any outside factors that could injure them.