Someone mentioned it's possible to read another project without cleaning up the workspace.
I never knew it's so easy to do (erease one line of code).
Please! Let's make this a feature!
The merged (lastly loaded) project's clips could be optionally colored to make them easy to spot (as pattern or instrument names may be duplicated, "bass" or "lead" for example).
Also an option to differentiate between pattern-space instruments (as opposed to song-space instruments) like grouping or coloring would be nice as a supporting feature.