Yes, depending on how you have the computer access set up. Does each son
have his own Windows login and profile? There is only one OneNote "My
Notebook" per user profile. OneNote will automatically create the proper
files for separate user accounts.
If each user on your computer has to select his/her name after Windows
boots up, then you should already be set up. If not, you can go to Start
menu | Control Panel | User Accounts (assuming you're on Windows XP) to
create separate accounts.