Looper should copy autosaved audio file when duplicated

[grough]

When a Looper module is duplicated, the duplicate retains a reference to the autosaved audio file that should belong exclusively to the original module. This is a bug, since two modules pointing to the same autosaved audio file will cause unexpected effects.

Expected behaviour: When a module is duplicated, the duplicate should point to a new copy of the autosaved audio file.