Open Access (Books) vs. Double Dipping: An Ongoing Struggle

The Hybrid Publishing Lab at Leuphana University, Lüneburg, Germany gives a recap on the difficulties to find alternatives in scientific publishing and it's policies.
The dispute amongst scholars and policy makers about which road to take to Open Access (gold or green) revolves to a great extend around the problem (or danger) of double dipping. It is widely acknowledged that publishers ought not to be allowed to charge twice for scientific publications, that is scholars and their public funders on the one hand and publicly funded libraries and readers on the other hand. On first glance this claim seems to be quite obvious as well as its solution appears to be trivial: when published open access a text has to be put online free of charge. Yet, that’s only part of the story.