When migrating a list with the Copy SharePoint Object tool, Sharegate displays the following error on a list:
Cannot overwrite the source list, try copying to a different location or renaming the item.
Using the Copy SharePoint Object tool, Sharegate doesn't allow migrating a list to the same scope where it would overwrite itself. Sharegate normally doesn't modify the source during a migration and expects the source not to change over the course of the migration. Overwriting the source list while reading from it could cause various unexpected behaviors during the copy and wouldn't produce any worthwhile results as the settings and the content of the list wouldn't even change.
Lists can be copied to the same scope only if they are renamed during the copy. This can be done by setting a different title and URL in the Copy Options: