The origins of Tanda Miki seem paradoxical but, as it is known, there is no such thing as a true paradox. The supposedly contradictory beliefs surrounding Tanda Miki do not violate the Immutable Mandates but, rather, require a deeper explanation.
The Watermelon People believe that Tanda Miki is responsible for the massacre of their people who were later recycled into new Watermelon people thanks to the advanced technologies deveoped at HG Dynamics. However, all records indicate that Tanda Miki did not exist prior to the Watermelon People and that both were a result of the recycling process.
A straightforward yet complicated question remains: how is that possible? How do the Watermelon People believe something that is untrue if it is not possible to lie? The answer is instructive, so I will leave you to determine it for yourself.