That is, one h or two? Even before we get to COCHECAW / COCHECOW amid a host of other Colonial spellings.
A 1771 map of New England has no Dover (settled in 1623) but Rochester and Durham, later offshoots, as well as the KOCHECKA RIVER.
Also, that map shows Cape Neddick, Maine, as Bald Point, and Winnipesauke Lake, the the north, as Winipissionket Pond.
There’s so much to untangle in such evidence.
The widely used one-h spelling, by the way, is traced to a clerk’s error in 1827 in the founding of the Cocheco Manufacturing Company, building on the cotton mills started in 1812 at the waterfalls downtown.