The symptoms do resemble Potato Scab, at least on the white potato, though it looks mild. If so, the lesions can be peeled off and the potatoes are safe to eat. In addition to the page linked above, Cornell has more information about Potato Scab and its management/avoidance options, including crop rotation (some suggestions of which are admittedly geared more towards farms than home gardeners), using scab-resistant cultivars, and checking on soil acidity (pH). A laboratory soil test can be useful if pH needs measuring, as it's more accurate (and has the benefit of analysis key nutrient levels) and easier to interpret than home test kits or probes.

Miri