You can clone with
Some albums in Spotify contain multiple discs. When I use a MPD client and browse to such an album, I see multiple tracks numbered 1, multiple numbered 2 and so on. The discs are therefore sorted in between each other and there is no way to see which disc each track came from.
A possible solution for this would be to prefix the track numbers with disc number for albums with multiple discs (101, 102, ..., 201, 202 and so on).
Our album data model should probably be updated to allow for adding this information. Of course we will need to figure out some way to get the mpd frontend to play nice with this as you suggest as well.
On a somewhat related side note, we might want to look at the musicbrainz data models to see if there is anything else we might be missing that they include.
When I opened #286 I forgot about this issue, these two things should probably be tackled together or deduped into a single bug.