Unexpected repeat item when using Dial Key #Ab

Operating System:
Windows 7

ISP:
Eastlink

Type of Internet Connection:
Optic fiber

Internet Connection Speed:
51.4mbps download / 10.3mbps upload

Date & Time:
3:50 am ADT

Frequency:
Unknown

Character Name:
Palutena

Race:
Mithra

World:
Fenrir

Main Job:
Thief 70

Support Job:
None

Area and Coordinates:
Lower Jeuno (I-6)

Party or Solo:
Solo

NPC Name:
Sweepstox

Monster Name:
None

Steps:
While trading Dial Key #Ab items to Sweepstox (using /item "dial key #ab" <stnpc>), received message "You cannot receive the item. Come back after sorting your inventory." Inventory still had empty space.

Discarded all abjurations in inventory from content older than Geas Fete. Interacted with Sweepstox. "Sweepstox: Ya's thought I threw yer prize away?! Prepostamarous! I's just tucked it away for safekeepin' is all." "Obtained: Neptunal abjuration: feet."

Continuing to trade Dial Keys #Ab, the same occurred again. Once more, on throwing away all older abjurations, I was able to claim a Neptunal abjuration: feet from Sweepstox.

Expected behavior: When Dial Key #Ab would produce an abjuration already in inventory, player instead receives a random goblin-themed item (examples include Hobgoblin Pie, Goblin Weel, Goblin Chocolate, Goblin Pie, Goblin Bread) and is not given the "You cannot receive the item. Come back after sorting your inventory." message.