don' listen to these other two.
Both are wrong john. My H27 has the same deal. The two lines that exit the aft of the boom are for reefing. It was called the Jiffy reefing system. It was even included on some boats like owers that only have one cringle on the main. The two lines were ment to go to two different cringles. So the main could be reefed in two different positions. I had an extra cringle put in. I rarely use it, if ever. It basicially is just another line on the deck. Might come in handy as a liffe line some day.