They should have it so vampires only get vampire stuff, and dawnguard only get dawnguard stuff.

Don't get too excited, I said it SHOULD. We probably can't even get it anyhow. >.<

haha yeah I saw that after I replied. Not gonna lie, I was pretty excited about it.

Is there any way to get Valerica's Vampire Royal Armor?

It's a different colour than Serena's and the one you find.

I want it badly too!

Unfortunately, it doesn't seem to be available to those who go Vamp.

As other have said it's a re-colour of the green cowl found in vanilla. It isn't the same model as Sarana's which looks more like a Thieves Guild/Linwe style.

It's also the same for the Vampire Boots and Gloves which can usually be found on Visiting Advisor quests for Gunmar at the Dawnguard Fort. (Save and reload until he gives you one of the quests concerning a Vamp posing as citizen)

There's a few of the Vampire Gauntlets in game though. They can be found on the random city NPC Vamps called "Visitor" as well as in the Valk Castle where the House Dres Dunmer is (upstairs to the left, beside the black Vampire Armour) and during the trek up the back entrance of the Castle (Soul Cairn quest) to the right of the Alchemy table where the lone Vampire woman is working.

I've found a couple hooded black robes, which I don't remember finding before Dawnguard was installed, but I haven't found any black hoods yet either.