If you want configure second report server in share point integrated mode it should not break the existing one as long as you use different report server database as opposed to scale-out deployment, since you have to rebuild your reportserver database for sharepoint. You have to understand that sharepoint integration mode should be part of sharepoint server farm.
check this link for further instructions
http://technet.microsoft.com/en-us/library/bb326407(SQL.90).aspx
However, there is another solution that i prefer is using sharepoint webparts, where you can view reports in sharepoint site without actually running in integrated mode.