Why am I getting a Yum repository filename conflict?

This means that you have created a repository filename starting with collabnet.

The repository file for the TeamForge installer begins with "collabnet-*.repo". If you have a customized repository with the same name, then the TeamForge installer renames the repository file with ".backup" as an extension and installs the repository file. It is better not to have any repository file name that begins with collabnet apart from the one that is installed by the TeamForge installer.