Don't show option already selected

Hello everyone,

I’d like to know if it’s possible to do the following: I basically have a select with a lookup table and “Use modal dialog for lookup.” I also have an “Option template.” What I want to know is whether it’s possible, as shown in the image, for the top circle to display an option that, as seen in the bottom circle, is already selected. The system currently handles this correctly, but my question is: Is there a way to prevent the option (top circle) from appearing if it’s already selected (bottom circle) without being added yet?

I hope I’ve explained myself clearly.

Thanks, everyone!

I tried with “check duplicate”, but this didn’t work

Yoy may try Ajax with API problem - #2 by arbei.