Normally it wouldn't glitch that way, unless you've attempted to port accessories or hair styles from different chronicle or server type where .dats or mesh points aren't allocated with hair attach points. There's also another way you could get this glitch and it's around the saving of the hair style within the char info. A full hair (2-slot) accessory tends to change the look of your hairstyle while you have it equipped - and my guess is that this change is overridden by the Beauty Shop setting another hairstyle on top of your character (different from the one that is carried out by the accessory alone)
You could debug the output of your current hairstyle - before and after beauty shop but I am not sure where you could compare that with what the client is currently displaying (my point is that on the server side you might be with a hairstyle G but the client to be displaying hairstyle H which would confirm Beauty Shop overlaps the accessory's priority hairstyle. I believe it's appointed within the grp date of the item but I might be wrong about that)