I just googled around a bit and found this:
You can have lprng bind to the same port provided you configured lpd.conf file correctly, but be cautious about security implications.
" LPRng uses the lpd_port=printer configuration option to set the port for the connections to a lpd server. By default, this is port 515, but can be set to other values. This port value is used to make connections to a remote lpd server. The lpd_listen_port=printer configuration option can be used to specify a port for the lpd to listen for incoming requests. If no lpd_listen_port value is specified the lpd_port value will be used as the lpd listening port."