@iasensio: I found an issue with !472 (merged) that would leave out one of my two displays when restarting the PowerDevil service. I added a second commit to this MR which finalizes your work of making restarts robust, building on the duplicate avoidance guarantees of this MR's original (first) commit.
If you have time (or anyone who doesn't fear row model updates), I would appreciate a review! Thank you :)