Yes, you can. When you have installed several versions of Gazebo, you could find them out in /usr/share/gazebo,/usr/share/gazebo5 or /usr/share/gazebo7 depending on what versions you have installed. The first one always exists and you can find a setup.sh file in it which indicates the path to your Gazebo model resources, server address and etc. So if you have installed more than one versions, you may have to be careful about this paths.
Another thing that you need to concern is that when you run ls -alF /usr/bin/gazebo it should output which gazebo are you using. For example, in my computer, the output is
lrwxrwxrwx 1 root root 12 Mar 22 01:55 gazebo -> gazebo-7.6.0*
which means I am using gazebo 7. If you want to use different version rather than this, you should directly point to the executable in /usr/bin or you could link /usr/bin/gazebo to another version.