Okay so this is mentioned nowhere on the wiki, but DRAY decides whether to copy non-energy or energy particles based on what it sees first in its line of sight. If it sees non-energy first, it'll copy non-energy; if it sees energy, it'll copy energy (and if it sees both, i.e. an energy stacked on a non-energy, it'll still copy non-energy). This is unlikely to be changed as existing saves already rely on this behaviour.