Every new login shows the minecraft domain with red and green separated by several pixels. Torches, for example, show double: one red and one green side by side. The landscape is unrecognizable.
The error has just appeared, and is the same for every log-in to Minecraft whether existing domains or a new domain. All other computer functions are OK including the list of Minecraft tools at the bottom of the screen. The error survives computer reboots.
I may have created the initial error by hitting a function key as I logged off one day, but have since pressed all 12 function keys in an unsuccessful effort to undo any such action.
Better known as stereoscopic 3D.
just disable it in graphics settings.