Lvl 61 Commando back armor blocks most back vanities.

[Futumsh]

I'll take a look when I have time. Back items should be hidden by vanity back items, so if some aren't, they need to be fixed.

Hrm, actually looks like a lot of back vanities are meant to be shown in addition to the non-vanity back, so not sure if we'll be doing anything to the items.
I can see about adding a 'Hide Back' option at the least.