You could well be correct, but do you have any supporting evidence? Anne daughter of William Radcliffe & Jane Killey was bapt 3 June 1759 in Maughold, as you say, but Radcliffe families in Andreas moved in and out of Maughold, and few stayed for more than a generation or so during the 1700s and 1800s. Anne's father William came from elsewhere - there are no William Radcliffes bapt in Maughold until Anne's brother William in 1766.

That was why I wrote that we were unable to make a definite identification of the Ann who married John Garret in 1787. However someone may have managed to do this - from Ann or John named as next of kin supervisor when a sibling died young leaving under age children (for example), or if Ann or John died young and their relatives were named in the same circumstance, or if they were named in a relative's will, or if they named Radcliffe relatives in their own wills, or if there was a marriage contract, or if her age was given at burial or on a M.I. - etc.
There are many Garrett Lezayre wills noted in Brian Lawson's index, but few transcripts - it would be helpful if Garrett researchers add to these.

We looked at Radcliffe sources without success, but didn't look at all Maughold wills, or possible siblings - so perhaps you have further information?

Sue