[Feature request] Multiselect fields that allow users to give the same value more than once or only once

[mxskylar]

Is your feature request related to a problem? Please describe.
I noticed that multiselect fields that pull values from the contents of a folder allow users to select the same value more than once:

Multiselect fields that have static values defined for the form only allow users to pick a value once:

Describe the solution you'd like

Sometimes I want to allow users to select the same value more than once. Other times I want to force them to select a value only once. Ideally this would be unrelated to whether or not I pull values from a static definition or a folder. I'd like to be able to pull values however is easiest no the constraints on users of my form—selecting a value only once or more than once.

Additional context

This is a small quality of life improvement request. The plugin is really great overall and has improved my workflow a ton. Thanks for all the hard work!