
We know now, not East Frisian, not Baltic and no luck for Denmark.
Sometimes it is good to re-think about it again. In the Dutch guild period, twice a master mark, where was it customary ?
In Groningen this was used from around 1725 for the highest silver standard, expressed by stamping both the master mark and the Groningen date letter twice.
In the period between 1798 and 1807 a master mark was sometimes stamped three times, namely on pieces that were sold in the province of Groningen, not in the city of Groningen, but the surrounding areas. Therefore not subject to a guarantee test and thus without Groningen year letter.
This tray, twice the maker's mark
RH. Perhaps we may attribute this mark to;
Reinder Harmannus
Hofman, registered in the dike village of Grijpskerk in the province Groningen.
He started before 1807 (French period, a turbulent time with many changes) and used
RH as master's mark. Later in 1812 he used RHH in lozenge. In 1814 he used the master's mark
RH under a clog, in a square.

He was baptized on 3 February 1771 in Grijpskerk (GR). Occupation: Silversmith. He died on 8 January 1826 in Grijpskerk (GR)
I mention him as a
possibility, unfortunately no example of his early master mark has been found yet
Peter.
Source;
Jean - Pierre van Rijen, Groninger keur Zilver uit stad en Ommelanden. WaarborgHolland Gouda, uitgave 2009. Gratitude Horst H. Arians