Two-sided?
It's in 'Page Settings' and 'Preferences>Score'.
What is this for?
I'm not sure if it's related, but in the navigator (in the trunk), the pages are laid out in the navigator: 1(space)2/3(space)4/5. What if you want them 1/2(space)3/4(space)5/6, or separately? The latter seems to be what's in 1.1.
Comments
It's for when you're printing out a score in double-sided format - ie a booklet.
That is why there 1 is on its own.