Was the procedure you adopted correct?

Something on your system disk you use may be wrong.

- download Sys 6.0.1 disk 2 image and put it on a vintage mac superdrive equipped

- download "prodos II extension" (part of IIe emulation card software) and put it on extension folder of a vintage mac.

- format and initialize an DD 800k prodos disk on a vintage mac

- burn the Sys 6.0.1 disk 2 image on a double density disk using Diskcopy 4.0

Hope this helps.