Yes, as I believe you can't have a Bladed "Two-Fer" (Or that I have seen yet) since the prefixes tell you what the attachments are. "Two-Fer" is to be considered as an "Internal Attachment"
The prefix comes from the sum of a weapon and it's parts, not the other way around. There are two accessory slots on a weapon. As far as I can remember, only one weapon in this game can get an accessory in that second slot (Captain Blade's Rapier from the Scarlett DLC). Every other (legitimate) weapon can only have one accessory.