FindGameObjectsWithTag returns extra prefabs nowhere in the hierarchy

This is brand new to me. Double-clicking a clone does bring it in focus in the inspector, in which it only has one component out of a bunch and everything is greyed out. Sometimes it doesn't happen, but once it does, it keeps on consistently happening until I restart the editor, in which case it stops happening for a little while. It generally causes one extra instance to appear, but one case had it spawn exactly fifty times.

If that's of any relevance, one of my scripts declares an array of GameObjects like so.

 GameObject[] others = new GameObject[all.Length-1];