there is probably an error in the /usr/share/dbus-1/services/org.xfce.calendar.service configuration file.
instead of "Name = org.xfce.calendar" there is a value of "Name = org.xfce.orage"
this causes the dbus-broker-launch [730] error: Ignoring duplicate name 'org.xfce.orage' in service file '/usr/share/dbus-1/services/org.xfce.calendar.service'

$ cat /usr/share/dbus-1/services/org.xfce.calendar.service
[D-BUS Service]
Name=org.xfce.orage
Exec=/usr/bin/orage

$ cat /usr/share/dbus-1/services/org.xfce.orage.service
[D-BUS Service]
Name=org.xfce.orage
Exec=/usr/bin/orage