i have noticed similar/same behavior. i have a dual-monitor setup, and not only does it appear to add a new desktop space(s) upon each boot, but it bunches all of them to my main left monitor, leaving only the minimum one window space for the right monitor. in mavericks and previous iterations, the desktop spaces i had on the left monitor would stay left and the desktop spaces i had on the right monitor would stay right. after tinkering with some other settings through a few restarts, i now have 14 desktops open, 13 of which are on the right monitor. i tend to like running with 6 desktops, 3 left and 3 right, safari on "desktop 1" and mail on "desktop 4". this is rattling my workflow to the core! help!