Hi ereino!
Sugar alcohols are sugar alcohols.
They are also known as polyols.
As far as "canceling out" when calculating net carbs, this makes more sense when you think of a product that has fiber and sugar alcohols, but still has remaining (i.e. net) carbs.
For example...
Total Carbs = 20g
Fiber = 10g
Sugar Alcohols = 4g
20 (total) - 10 (fiber) - 4 (Sugar Alcohols) = 6 Net Carbs
In this example, if the sugar alcohols equaled 10, net carbs would equal 0 (zero).
One caveat is that some sugar alcohols will, with some individuals, be metabolized like net carbs by causing blood sugar spikes.
Malitol is one of the worst offenders in this way.
That's why it's so important to track and record EVERYTHING you eat to see how your body responds.
What might not make a difference to one person, can cause stall outs or gains in another!
Tony