VideoPress: Videos listed more than once if the file is duplicated on the media library

Not sure how that happened, but it seems that WPML creates a copy of the video entry in the media library when adding another language. This causes the video listing on the plugin's dashboard to list the same video more than once.
We need to find a way to deduplicate the data on cases like this.

Start in the VideoPress plugin dashboard listing and reproduce the case where WPML adds a duplicate video entry in the media library. Trace how those entries are gathered and where duplicate records can be removed. Done means the same video appears once while distinct videos remain listed, with a regression check for the duplicated-file case.

Written by the indexing model from the issue text.