I can’t see an obvious way to do this, though other imaging and backup solutions will eg Macrium Reflect, Acronis, etc. can live image a Windows/Linux dual boot system from Windows and have the Linux partitions included in the image (or even image them separately).
How does one specify UrBackup to image these? The only documented method for imaging seems to be to specify volumes by drive letter, and letters aren’t available for Linux partitions.
If there isn’t currently a method, then please move this topic to Feature requests 