Dgad, my solution for classical LPs with multiple composers is to file one of three ways: 1) under the composer whose work on the LP has the greatest significance for me, or 2) file under the composer already taking up the most space on the shelves, or 3) when there are a whole host of composers with many short works, file under a generic category (e.g., "Baroque," "Brass," "Marches," "Renaissance"). In the generic groupings (#3), I'll typically sort by label.
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