I do agree that if a dog can handle it two litters in a row is fine but needs to be approved first by the vets. Doing two litters a year for five to six years is an average practice for Australian Labradoodle ILA members. That's Twelve litters...
I disagree with such aggressive breeding practices on dogs, I think it's inhumane and cruel. They are not wolves that have an average life span of four to five years and only come into heat once a year.