It is just an effort to get you to part with your money for a cheap Chinese piece of marginal junk.
And the only truly successful as seen on TV products I can think of that were good enough to surpass TV ordering and become household products are oxyclean and Flex seal.
Still advertised on TV and of course the flex seal guy is still gluing boats back together, but they're no longer ripping people off with a " buy one get one free " offer.
Seriously why do you have to pay seperate shipping and handling on the free one when it all ships in one box.