They only archive original sources, not transcodes. With that said I'd guess they'd start archiving non sources if there was space.

This helps somewhat, but there might be many original sources of the same thing, more or less depending on what we are talking about ?

Without doxxing myself or the site it's video so they prioritise by format. So it would go something like.

UHDBD > UHDRemux UHDWebRip > HDBD > HDRemux > HDWebRip > DVD9 > DVD5

With multiple sources within each tier treated equally.

The general thought process is more about the site disappearing so the focus on sources makes more sense and transcodes can be created trivially if needed for a theoretical new site as needed.

With the IA this is unlikely to be an issue as they'd just want to make sure each torrent has seeds so no real need for prioritization around sources.