As long as they do not claim that the software contained on the chips is the intelectual property of the seller or tuner, there is no difference to selling a modified cylinder head or a modded throttle body.

But, I do see your point with it being software. However, also bear in mind that you can modify your operating system by way of themes and other programs without being in breach of copyright, and if your software was purchased retail you can sell it on too.

Tough one to call as there are so many different examples of what could and couldnt be a breach of copyright / intelectual property etc...