Naming trailers with media source tags

How should I name local trailer files if I am using media source tags on my movies? I know how to name them if there’s no media source tag. {movie}-trailer.{ext} This works:

A Bridge Too Far.mkv
A Bridge Too Far-trailer.mkv

But, when I add the media source tag to the movie, Kodi shows the YouTube trailer, suggesting that it doesn’t recognize the local one. For example, this doesn’t work:

A Bridge Too Far.dvd.mkv
A Bridge Too Far-trailer.mkv

I also tried this, and it doesn’t work either:

A Bridge Too Far.dvd.mkv
A Bridge Too Far-trailer.dvd.mkv

If it matters, I’m using Confluence and Kodi 16.1.