I found different versions in the English and German Wikipedia articles about the Apollo 6 flight.
"Das zweite Triebwerk wurde vom Steuerungssystem fälschlicherweise deaktiviert, weil die Steuerungsleitungen zwischen den beiden Triebwerken vertauscht waren."
Translation: The second engine was shut down erroneously due to swapped control cables between the two engines.
The English version is just about two independent engine shut downs.
I found no other sources confirming the German version. Such a cabling error would be difficult to prove using telemetry data only. But what else could prove the error after the flight? Is there any other information about the Apollo 6 engine shut down?