<para>
This option causes the duplicate filter to remove any additional waypoint
that has the same coordinates (to six decimal degrees) as a waypoint that
came before.  This option may be used to remove duplicate waypoints if the
names are not expected to be the same.  It also might be used along with the
<option>shortname</option> option to remove duplicate waypoints if the names
of several unrelated groups of waypoints might be the same.
</para>
