Do pathological opposites cancel each other out? Do all patients with both hypermobility and spondylarthropathy fulfill a criterion of any disease?

When a patient with hypermobility syndrome suffers from ankylosing spondylitis or seronegative spondylarthropathy with spinal stiffness, a part of the mobility criterion of the one disease may be "eliminated" due to the other illness. These two cases may represent typically such opposite effects on mobility.