Conditions may vary from place to place/stretch to stretch but in my experience any licence issued for a demarcated area allows only one rod in use at any given period. You can take as many rods with you as you like but only use one at a time. Sometimes the lure to be used is very strictly limited. Enforcers can be obvious or proceed with stealth but so long as you are never observed to break the rules you are unlikely to fall foul of them. Two people (e.g. parent and child) being there with two rods is OK so long as only one is fishing with a single rod at time - unless you have a licence specifically covering two rods/people. This is normally not at all like in some places in the USA where having an unopened can of beer on the floor at the back of the car constitutes driving under influence.