Just got this from another forum member!
Glad there is some truth to it here!
Interestingly enough, this is technically true. The question is if the concentrations in potato peels and cans are high enough to have the same effect. Doing a spot check of the MSDS for three commercial Creosote remover products, the active/ingredient common to them is manganese acetate. (The actual percentage of manganese is withheld as a trade secret on the MSDS)
Both steel and aluminum cans contain manganese as part of the alloy (~ 0.35 to 1% manganese) and the average potato contains 0.3 grams of manganese (most of which is concentrated in the skin).
So potentially, they could work the same as the commercial products, converting the sticky tar-like creosote into the easier to remove flaky creosote.