Switching to twoside has different effect for main text than for frontmatter

[Wollipolli]

I use the generic template. After I switched to twoside (Dissertate.cls:14) - the frontmatter is formatted with a smaller inner margin, the main text has a smaller outer margin.
Since I did not define an offset for binding, I expect the outer margin to be larger by default, thus something is messed up with the main text. Also the numbering is weird, as suddenly even numbers are on the left. But this might be expected behaviour for an odd page frontmatter.
Does anyone have any ideas?