Separating most likely really depends on them. If for the most part the scuffles don’t escalate, you might get away with them remaining together. You’ll have to gauge whether separating after surgery is for the best or not. Some many pine for their companion and become depressed. However, post surgery they may also be more intolerant of each other and fight more. So i’d recommend clearing some time in your schedule so you can closely monitor them after surgery. Id you do need separate them straight after, having a pen barrier where they can still see, smell and lie next to one another might help maintain a bit of the bond.
I had mother-daughter pair spayed fairly recently. When the younger ones hormones arrived, it triggered humping in both of them. It literally stopped straight after surgery. I was able to keep them together in their room though they did chose hiding spots away from each other for the 24-48hrs after surgery. After recovery, they sort each other out & also become social with me again. It was really nice to see them calm and content again.