Duplicate GEM Protection Check Inventory

Hello,

The duplicate protection in options does not seem to prevent duplicate gems when the gem is in inventory or stash. I have attack & support gems that are identical. I have no means of destroying or refunding. So I put in guild stash. Would be great if dupe protection prevented all duplicate buys or provided a means to convert back to currency,

Starting out I was still not yet familiar with names of my skills and trusted the duplicate option to not let me buy anything I already bought.

Thank you!