I believe two versus one in-haul line was based on weight of the cannon. On the Boudroit drawings of the Bonhomme Richard, the main gundeck has rings for two in-haul lines on the main gun deck. Next deck up, there is only one ring for a single in-haul line. See photos below:s
Main Gundeck (two rings)
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Middle Deck (smaller cannons and only one center ring for in-hauling)
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I'm not sure what the rings are directly behind the carriage wheels??? Looks to me like they would cause big problems while the carriage rolled back.