Before the mid 18th century, only two tackles were issued per gun. After this, three per gun were issued, but never more, so it is unlikely that two tackles were hooked to one side of the gun. The tackles at the side of the gun would have been hooked to whichever ringbolt in the ship's side best served the need at that moment: to traverse or to run out. Doubtless hand-spikes or crowbars were still needed to assist the traversing.
The increased traversing ability led to changes in the way that the breeching rope was attached to the cascabel at the breech. For many years, it was cu(o)nt spliced, or looped and seized, around the button, but if the gun was fired at any angle other than 90 degrees to the centre line, one side of the breeching rope would pull taut before the other. The final solution, after experiments with passing the rope through thimbles stropped to the button, was to cast an integral ring at the cascabel, which allowed the breeching rope to be adjusted from side to side. This appeared in the Blomfeld pattern guns, a greatly improved design, which were put into production just in time for the wars with revolutionary France and then Napoleon.
All the best,
Edited by Mark P, 30 December 2016 - 10:44 AM.