Simple answer - Yes
To clarify, theh weight of the carrier and its bikes sits on the tow hitch and thus uses some of the allowable loading for the hitch, and its effect can be considerable - most bikes weigh in excses of 10Kg adn teh carrier is probably a further 10Kg so for a typical tow ball load capacity of 75Kg, with 2 bikes and carrier, teh available nose load for teh trailer would be 75 - 30 = 45Kg
Most forum users eventually go for either puting the bikes in the caravan, or on a car roof mounted carrier.