You sometimes see PuTTY icons on the side of the terminal (example below).
This is a new security feature in PuTTY 0.71. It is meant to signify that PuTTY itself is outputting those lines and not some remote server. Full details are available here.
Currently, mRemoteNG does not have a feature to support editing or creating connections in bulk. See :ref:`bulk_connections` for more info on this.