My wife and I will be sharing my nexus 7 :-( that is why she let me have one lol. Any way,
According to Jelly Bean | Android Developers:
Users can install and uninstall apps at any time in their own environments. To save storage space, Google Play downloads an APK only if it's not already installed by another user on the device. If the app is already installed, Google Play records the new user's installation in the usual way but doesn't download another copy of the app. Multiple users can run the same copy of an APK because the system creates a new instance for each user, including a user-specific data directory.
Separate names with a comma.