I don't find this surprising at all. Sample variation is certainly a thing from headphone to headphone, but it would have had to have been a pretty huge variation to significantly alter the conclusion on the Z1R. Different rigs, slightly different samples, and different people reviewing. Only one of these things is subjective, and that's probably where the biggest discrepancy occurred.
If nothing else, this is a good reminder for everybody: squiggly lines are only directly comparable to the other squiggly lines measured on the same rig.