Cannot discard duplicate Master Recipe Book

Date & Time: 07/02/2020 1:59PM EST
Frequency: Any time
World name: Gilgamesh
Character name: Seraphus Highwynn
Class/Level: Leatherworker 72
Party or solo: Solo
Steps:
1. Buy a "Master Leatherwork VII"
2. Place it in your Chocobo Saddlebag
3. Buy a second copy of "Master Leatherwork VII"
4. Use one copy.
5. The extra copy cannot be discarded, as the discard option is greyed out.


In brief, the game runs a check when you purchase a Master Recipe book to see if you already 1) learned the recipes already before (preventing you from buying a second copy), or 2) checks your inventory and retainer's inventories to see if there is a copy existing there already. The game does *NOT* check your Chocobo Saddlebag for a copy, therefore allowing you to unintentionally purchase duplicates. Because of this, I now have a permanent, non-discardable item in my inventory.

https://i.imgur.com/sbmHjnl.jpg