Not sure if this is intended, but unidentified dye from non-PvP sources (i.e. drops, BLC, etc.) does not stack with the unidentified dye from the PvP reward chests. They also have different pop-up texts and restrictions:
Non-PvP: Double-click to identify one random dye color which can be unlocked for one of your characters or recycled at the Mystic Forge.
Consumable.
Crafting Material: Artificer (400)
PvP: Double-click to identify one random dye color which can be unlocked for one of your characters or recycled at the Mystic Forge.
Consumable.
Account Bound.
Seems like the PvP sourced UnID’d dye should be the same as the non-PvP sourced dye.