To really make the song mode useful it should be possible to not only duplicate clips (into/within it), but to be able to link(-ed duplicate) them aswell (like drum tracks typically have repeating sections that need to be copy pasted otherwise). This means that a clip that is linked into multiple locations will adapt everywhere whenever the source clip changes.
This is necessary because currently all occurrences of a clip in a song need to be manually deleted and the source clip duplicated into their places again whenever one wants to make some adjustments to it which is unnecessarily tedious.