in services_dyndns.php

						$int = strtolower($if);
						$real_int = get_real_interface($if);
						$filename = "{$g['conf_path']}/dyndns_{$int}dyndns.cache"
change to
						$int = strtolower($if);
						$int2 = "{$int}{$vals[$j]}";
						$real_int = get_real_interface($if);
						$filename = "{$g['conf_path']}/dyndns_{$int2}.cache";