I have reported a duplication exploit in PM on Discord.
This issue serves as a mere reminder of that report.

Per the discord message

All you have to do is go into the Account Transactions interface then:

• place any item in the place where you would deposit Moneta coins (so as to occupy the slot)
• make sure you have a free hotbar slot
• shift-click any item in your inventory (so as to quick transfer it to the previously occupied slot)
• the shift-clicked item will be duplicated in you free hotbar slot