Control: tags -1 + patch In the Jessie version (2.3.1-1), which is also the latest version in sid, parallel-scp works with multiple source files.
For parallel-rsync there is a patch available at https://github.com/lilydjwg/pssh/commit/25de15b0e4f72d658f7783c32a905edd72ee383b that adds the functionality to rsync multiple source files in one go.