Microsoft Data Protection Manager 2010 will not let you backup different protection groups to the same tape.

In DPM 2010 Administrator Console, Management -> Libraries tab, you can check current status of “Colocation of data on tape” property.

To enable colocation of data on tape, open DPM Management Shell and execute the following command:

Set-DPMGlobalProperty -DPMServerName <DPM Server Name> -OptimizeTapeUsage $True

To disable colocation of data on tape, execute the following:

Set-DPMGlobalProperty -DPMServerName <DPM Server Name> -OptimizeTapeUsage $False

Even when you enable colocation of data, certain conditions apply. Follow this link to find out more.