During the street building project on the sump, while everyone was digging away, two extra shovels appeared in my inventory. Checking at a shrine indicated that I had 3 shovels. I was able to drop one of the extras but the other one was occupying the space of my bag of music blocks, and although the menus for the shovel seemed to work, I couldn't actually drop it. Reloading disappeared that shovel and restored my bag (yay!).