Unfortunately multi-head support is not implemented in the lock screen infrastructure and I consider it as unlikely that we will implement it any time soon. It's nowadays difficult to configure (some drivers do not support such modes any more) and it needs significant changes in our lock screen architecture to support it. Changes I plan for 5.3 might make it easier to support such setups in a secure way.
Unfortunately multi-head support is not implemented in the lock screen infrastructure and I consider it as unlikely that we will implement it any time soon. It's nowadays difficult to configure (some drivers do not support such modes any more) and it needs significant changes in our lock screen architecture to support it. Changes I plan for 5.3 might make it easier to support such setups in a secure way.