Cannot delete Quest Item from regular item inventory

I have a "Serpent Chocobo Issuance" in my inventory from the My Little Chocobo quest that I cannot delete and I cannot sell. It's a quest item that's only available from the grand company vendor for that single quest. You trade it in to get your first chocobo mount, you may remember. Here's what happened:

I bought one Serpent Chocobo Issuance for the quest and turned the item in to the quest npc, but before I named my chocobo and completed the quest, I mistakenly went back to the quartermaster and bought another Serpent Chocobo Issuance. Then I went back to the quest npc, named my chocobo, and completed the quest, but once I finished the quest, I still had the second Serpent Chocobo Issuance stuck in my inventory, not the quest inventory, but my actual inventory.

I can't sell the item, I can't discard the item by dragging it out of inventory or right clicking it and clicking discard. There's no way I've found to delete the item. The item is only on the vendor for the duration of that one quest.

I filed a support ticket to try and get it removed from my inventory, but the response said it wasn't a bug and I should read forums / talk to people / etc. to find the answer. Since then I have re-filed the ticket many, many times, but with no answer. I can't sell it back to the vendor, I can't drag it out of my inventory, I can't repeat the quest. There's no solution I have found, and it's in my inventory permanently.

Can this issue be escalated and figured out?

Thanks for your attention.