We've recently had three Cheshire backstools with remarkably similar carving (and a fourth that may be related. Two, A and B (which are currently for sale as a near pair) have virtually identical carving, though the framing of the panels differs. The third, C, has carving that is a variation on the same theme. and its framing rails are the same as on B. A and B have higher quality carving -- better defined, crisper, and with a stronger design aesthetic. Actually, we think B has slightly better carving and design than A, though the acorns on A are clearly superior.
But such differences are typical of handwork done as efficiently and economically as possible. A, B, and C must all be from the same shop, and we're guessing by the same hand.
Why the same hand? We don't know much about seventeenth-century workshop methods, but it does seem that carvers did not copy from patterns on paper nor from previous carvings, but that they held the overall design in their heads. There is no sense that either A or B is the original and the other a copy, or that C is a derivative from B. Much more likely is that all three are products of the same imagination, the same blue-print-in-the-mind.
D is more problematic. It appears to share the same basic design structure, but it is stiff and angular: the foliage does not flow from the flower stems. The framing rails are similar to those on B and C, so it may be from the same shop, possibly by an apprentice who had not internalized the design. Or maybe it's from another shop altogether, trying not very successfully to copy the popular design of a competitor. Who knows?
For more details on A and B here.