The decaf I buy states they have close ties with the farmers. The company they use for decaffeination seems to be a service-oriented company. You send them the raw coffee, they decaffeinate it, and then send it back with recommendations for roasting.

So, the "roaster" (if they don't use a separate company for that) does have the ability to select the exact same beans between their decaf and regular coffee products. Whether they sort the beans they get from the farmers and choose which go to be decaffeinated according to some criteria, is a separate thing.