There are other William Kelly entries in Michael in 1744, 1745, & 1748, in the Familysearch "Isle of Man Parish Registers, 1598-2009" but the source isn't clear (to me), and as I can't see the same ones on the IGI, I wonder whether they can be submitted entries - although they do say Christening, not birth.
Wm Kelly
Isle of Man Parish Registers, 1598-2009
christening: 12 May 1745 Michael, Isle of Man
father: Wm
mother: Ellinr Caine
Wm Kelly
Isle of Man Parish Registers, 1598-2009
christening: 12 May 1745 Michael, Isle of Man
father: Wm
mother: Ellinor Caine
Wm Kelly
Isle of Man Parish Registers, 1598-2009
christening: 12 May 1745 Michael, Isle of Man
father: Wm
mother: Ellinr Caine
Wm Kelly
Isle of Man Parish Registers, 1598-2009
christening: 2 September 1744 Michael, Isle of Man
father: John Kelly
mother: Esthr Kelly
Wm Kelly
Isle of Man Parish Registers, 1598-2009
christening: 15 January 1748 Michael, Isle of Man
father: Thos
mother: Jane Quayle
Sue