According to published FISH and PEASE researchers, it wouldn't be possible for the two Marys to be the same woman, the timelines and their locations conflict (see the attached).
I also found this, "Gershom Moore married Mary the widow of Jonathan Fish, leaving sons Gershom and Jonathan".
That was found in:
The annals of Newtown in Queens County, New-York : containing its history from its first settlement, together with many interesting facts concerning the adjacent towns : also, a particular account of numerous Long Island families now spread over this and various other states of the Union
New York: D. Fanshaw, 1852, 441 pgs.; pages 327, 328
I am not related.