Hi
Welcome to Rootschat

Both couples seem to have a son called Adam
William's father was William (deceased)
If they used the traditional naming convention, then Adam should be the second son and William the first ~
Tarbolton1750 William
1754 John
1755 Adam
..........
Ayr1754 William
1756 John
1759 Adam
so...............................
The couple married in Ayr and at that time Adam Lees was deceased.
My vote would be for them to be the Ayr couple but you'd need to do further checks-
Other children of Adam who might be worth chasing for any hints ~
1732 John
1734 William
1736 Elisabeth
Also, have you checked the MIs for Craigie, Tarbolton and Ayr and looked at the marriage/banns for the Tarbolton couple*?
I only have the MIs for the Carrick area of Ayrshire
JL
* I don't see the marriage/Banns of the Tarbolton couple on SP - can you give more info on them, please?