Yes, you can install multiple versions of Xcode. They will be installed in separate directories. I found that it is best to install the version that comes with your Mac, and then install the downloaded versions, but that probably doesn't matter much. For more information, see Apple Developer Connectivity Page.
It is easy to have multiple Xcode installations.
The installer has a drop-down box for the location ... you just need to choose a new location when installing the beta version.
Apple dev ( / Apple dev): https://devforums.apple.com/message/40847#40847
- XCode, , : http://iphonedevelopment.blogspot.com/2009/03/multiple-developer-tool-installs.html