[zoombini]

Tesco's could be reasonably selling them having bought them in good faith from thier supplier. If the supplier to Asda has broken a contract that tied them to selling the books only to Asda then Tesco's have done nothing wrong in buying them, its the supplier who did the wrong.
Any lawsuit against Tesco's will fail.
Its the wholesaler that has sold them to Tesco's in the first place, that needs suing.

But what the heck, they are all the same big company anyway...lol