Remove existing ddns provider when changing ddns settings

src/freedombone-ddns

     fi
 
     if ! grep -q "$DDNS_PROVIDER" /etc/inadyn.conf; then
+        # remove entry for any previous ddns
+        sed -i '/^system $/,$d' /etc/inadyn.conf
+
+        # add the new provider
         { echo '';
           echo "system $DDNS_PROVIDER";
           echo '  ssl';
             echo "  password $DDNS_PASSWORD" >> /etc/inadyn.conf
         fi
     else
+        # change username/password for an existing provider
         if [ "$DDNS_USERNAME" ]; then
             sed -i "s|  username .*|  username $DDNS_USERNAME|g" /etc/inadyn.conf
         fi
             sed -i "s|  password .*|  password $DDNS_PASSWORD|g" /etc/inadyn.conf
         fi
     fi
+
     systemctl enable inadyn
     systemctl restart inadyn
 }