You need use the shortcode [lfh-map]
before each gpx shortcode :
[lfh-map]
[lfh-gpx src=url_to_stevenson5.gpx title="Trail 1" color=red width=8] description[/lfh-gpx][lfh-map]
[lfh-gpx src=url_to_stevenson.gpx title="Trail 2" color=darkgreen width=8] description[/lfh-gpx]