Yes, sp Tenango del Valle is a form of duoformis. It come from Tenango del Valle which is in the state of Mexico, I believe. This is rather further north than duoformis is usually found, being Puebla and Oaxaca mainly. But it is known from Morelos, and therefore a spread further north west into Mexico state is not unreasonable.
I picked up what is supposed to be a white flowered form at a cactus meeting last year, but it hasn't yet flowered for me, but its a little early for them to flower here in the UK.