I have always found this kind of policy silly.  I mean, what's the point?  If you make one enemy list a copy of another, you just give up that enemy list having any meaning.  Unless guild enemy status has some mechanical consequence I don't know about, I don't see a point.

I try to maintain it so that to become a Serenguard enemy you have to do something specifically against the Serenguard guild itself, not just against the commune, just so it still means something.  But other Serenguard are a bit more trigger-happy with the enemy status so a lot of it is just a meaningless reflection of an already-existing enemy list.