1. About the bug. The algorithm that detects monitors overlapping must be a little "smarter". It's solvable, just need some time to fix. You can use "active-monitor" as workaround.
2. You still will have some issues with your monitors even with that fix.
Each your monitor displays the same area (see attachment). Search "lightdm dual" or "lightdm resolution" for fix.
1. About the bug. The algorithm that detects monitors overlapping must be a little "smarter". It's solvable, just need some time to fix. You can use "active-monitor" as workaround.
2. You still will have some issues with your monitors even with that fix.
Each your monitor displays the same area (see attachment). Search "lightdm dual" or "lightdm resolution" for fix.