Goggle Sites offers a feature called "Break the Lock" which will allow saved edit changes to override on another when two people are editing a page. Find out how this feature works and what the known problems are that Google is currently working on.
What are Locks in Google Sites?
Google Sites lets multiple users create and edit web page content within the sites system. Since a Google Sites owner can share their online workspace in the Sharing Lab, the chances for multiple people editing content are lessened but there is one area that can create a problem and that area is known as "Locks".
In the Google Sites editing menu there is the lock icon and by clicking it you can break the lock top open the editing up for multiple users on your Google Sites web presence. Here we take a closer look at these locks, so that you can break them open as needed for use. More information on other functions of Google Sites can be found through Editing Pages in Google Sites and Site Settings for Google Sites.
How to Break the Locks
Breaking the lock allows a site editor with permissions to start editing a page that is currently being edited by another user. By breaking the lock in this way, each user may end up with problems in their saving capabilities. If the other user "saves" and then logs off of the Google Sites system while you are still on, none of their edited work will be saved. The same is true if you decided to log off before they do, then your work will not be saved either.
The best way to get around this problem when working in Google Sites and choosing to break the lock is to wait. If you are the main admin or the creator of the site you have two options to ensure that your work will be saved. Your first choice would be to just wait the other user out. If you stay online and logged in to the system then when they log out your changes will override any saved work that they did on that page. You could also choose to kick them from the system, which will override their changes once you have saved under your own log in.
Recently, Google Sites has had some issues with breaking the lock not working the way that it was intended to work. They are working to correct the problem but if you encounter an issue will using the break the lock feature, you can have Google manually release the lock from their back end. When someone in Google releases the break the lock feature, the last saved edit to that page will have their name on it. If you do encounter an issue, Google asks that you go to the following Sites Help Thread and leave your Google Sites URL in the thread. Google will then take your URL information and fix the issue from the back end.
*images are GoogleSites screenshots