An item with same key has already been added

when I restore a database from the interface, it says Screen Shot 2020-01-11 at 10.35.04

any idea?

When you got this error. Please give more information.

thanks for getting back @VehbiEmiroglu

it is when I do Settings > Database Backup > Restore Database

it used to work, but stopped work on 5.2.26 12/4/2019 DB 153-153

I have tried to clear database and rebuild index, all not possible