Duplicate videoUrl check before import/export

[itmagpro]

Checklist

• [ ] This feature I'm requesting is already implemented in yt-dlp.
• [ ] This feature is merely a UI/UX update.
• [ ] This feature is suitable for primary users with little knowledge about yt-dlp.
• [ ] This feature is available for most websites, not only the video platform I use.
• [ ] This feature is suitable for a large variety of videos.
• [x] This feature is not going to conflict with many of the existing options.

Is your feature request related to a problem? Please describe.

When you export to json file from parent device, then import this file on other (child) device and add some video then export fom child and import to perent, - then in result we get many video duple ;(

I try export only url and then sort -u, but seal not support bak import only url ;(

Describe the solution you'd like

Propose add duplicate videoUrl (not id) check before import/export.

Video link

No response

Additional context

No response