Well, I can't remember off the top of my head, but don't the sidebars come with div classes/ID's when they're output into the HTML? It's been a while since I've used them - but I thought if you used more than one, they have a set ID or class to them.
I also thought there was a given tag that you used in the sidebar - yes...I remember. Normally, you use something like:
if ( function_exists('dynamic_sidebar') && dynamic_sidebar() to enable the sidebar. With the second sidebar, I believe you change it to:
if ( function_exists('dynamic_sidebar2') && dynamic_sidebar2()
or something like that. They talk about this on the widgets site (automattic.com).