If you mean castrated, yes - when they were little things, before we even got them. And we’ve had them for five years, with no problem like this.
I had a cat once who lived for 20 years; but I figure these are pretty much ‘early-middle-aged’ now, as cats usually go.
We are going to take the ‘instigator’ to the vet, to see if there may be a problem that we can’t discern. He’s the smaller of the two, but thoroughly intimidates his larger, more peaceful brother.