I have to say the cup marks on both these stones look fairly convincing to me, the decorated upright nearby and the cup marked stone in the Wet Withens cairn demonstrates that there was certainly some tradition of carving stones in this area. I wonder if a thorough investigation of the moor would turn up more marked rocks?
Perhaps 20m NNW of the Stanage Cairn is a rock with a possible 10 cup marks on it's top, 5 of them are hidden under a carpet of heather.
There is a stone close-by that also has 'hollowed' marks but these are thought to be natural. Because of this second stone Barnatt and Chums are still debating whether the 10 cup marks are natural or not.