how to keep sync of 2 iphones seperate?

You can sync multiple iPods and/or iPhones with the same iTunes library and iTunes account on one computer and each device can have its own sync preferences with iTunes.

Under the Music tab for your husband's iPhone sync preferences, he selects the iTunes playlists and/or artists and genres that he wants transferred to his iPhone. The same under the Apps tab and under the Photos tab for his iPhone sync preferences for the apps and photos he wants transferred to his iPhone.

If both iPhones are syncing contacts and calendar events with the same Outlook data, then the contacts and calendars events in Outlook will be the same on both iPhones.

Garbage in = garbage out.

uncheck contacts and photos when syncing.

If you both want to sync contacts via the computer, you will need to have two separate user accounts. You should also consider using a service like MobileMe or Gmail, which would allow you to sync contacts and calendars via the web instead of the computer. If you chose to have two separate user accounts, you can still share music by keeping the iTunes library in a shared location (a little different setup depending on if you own a Mac or PC).

Hope this helps.
Brian