The two additional old phpMyAdmin versions (2.7.0-pl2 and 2.6.4-pl4) included with the Virtualmin Script Installers are obselete and no longer supported. They haven't been updated since 2005 and probably contain bugs and security issues. They are no longer easily available for manual download from the phpMyAdmin web site.
If we need to keep around old releases, they should be updated to the last one or two major releases. This would currently be 2.9.2 and 2.8.2.4 in this case. However, the phpMyAdmin web site states "Note: security fixes are included only in the last stable and development versions." Therefore, we should not be distributing anything older than the last major release (2.9.2 in this case), simply to allow users time to upgrade to the latest stable version.