I have used last.fm since 2005 and bought my first Sonos devices in 2012, and I have suffered from the double scrobble problem when using Spotify that has been discussed in question threads for many years. If I remove scrobbling from Sonos but play Spotify through Sonos, no scrobbles are registered. If I have last.fm as a service I get two scrobbles for each track I listen to.
I have a fix for this problem. Of sorts. I bought a Sonos Roam, a brilliant little speaker, that has the ability to connect to both my Sonos system via wifi and my mobile device via Bluetooth. So, I connect to the Roam with Bluetooth, control Spotify with my phone, never use the Spotify service in Sonos, and then connect the Roam to my Sonos system and at last, no more double scrobbles.
of course a dedicated in-Sonos coded solution software update would be much better, but this works, so I’m happy.
Now I just need to get the Beam I received today to talk to my Sony Bravia TV.