No, it's legit, NotFuzzyWarm answered based on your question which is wrong, to begin with, your problem has nothing to do with the voltage, it's just hex code that is stored somewhere in the hash board, starting from the S9k series onwards, you can't just mix hash boards from different miners, every model will have like 2-4 different codes, usually labeled as 0,1,2,3, the kernel log will display that at the beginning, which is why you should paste the FULL kernel log so that we can help you further.
With that being said, since there is always a 25/33% chance that the mix will work, you don't simply assume your problem is just mixing the boards, there are many other things that can cause the problem you describe, so please post the kernel log and a screenshot of the miner status.