You can take build configuration settings from the project-config.xml file of the corresponding project, fix build configuration id and name and add this configuration snippet to the desired project-config.xml of another TeamCity server.
Also you need to take corresponding VCS roots from the vcs-roots.xml file (or change use existing roots, but you will need to find out their ids).
Do not forget to backup config files before modifying them.
You can take build configuration settings from the project-config.xml file of the corresponding project, fix build configuration id and name and add this configuration snippet to the desired project-config.xml of another TeamCity server.
Also you need to take corresponding VCS roots from the vcs-roots.xml file (or change use existing roots, but you will need to find out their ids).
Do not forget to backup config files before modifying them.