Second associated issue in line 1824 of functions/admin-functions.php
if ( $option['face'] == $font['name'] AND !strstr($fonts, $font['name']) ) {
needs to be
if ( $option['face'] == $font['name'] AND !strstr($fonts, $font['name']) . "|" ) {
Because "PT Sans" matches "PT Sans Narrow", so including the bar in the search ensures an exact match.