Hi Stewart,

Indeed, this is the default configuration of the FileSelect component.

A useful and flexible approach for such scenario would be to allow cancelling the OnSelect event based on specific condition. Thus, one can set their desired business logic for preventing the files from selection - could be duplicated files as per your request or something else.

The FileSelect currently does not provide option for cancelling its events. However, we consider it a valid feature that could be added in a future version of the product. Having this in mind, I tweaked the title a bit to cover the specific request. I also added your vote to increase its popularity as we are prioritizing the feature requests implementation based on the community interest and demand. As a creator, you will be notified via email on any status updates and thus you will easily keep in track with the progress of the feature.

Regards,
Nadezhda Tacheva
Progress Telerik