According to the "Sterbebücher" (death records) of Auschwitz, Jacob Dingsdag was murdered there on 7 September 1942. This date is different from the official date of death as determined by the Dutch Ministry of Justice after the war. For the time being, the website joodsmonument.nl, list only the dates of death, as published at the time in the "Nederlandse Staatscourant" (Dutch Government Gazette) by the Ministry of Justice.
Sterbebuch Auschwitz (death record)
Official death certificate nr. 490 for Jacob Dingsdag dated 20 July 1950