⅙ Thaler / 6 Mariengroschen - Rudolph August and Anthony Ulrich

Rudolph August had ruled Brunswick-Wolfenbüttel alone for over two decades before reluctantly accepting his younger brother Anthony Ulrich as co-ruler in 1685 — a partnership driven less by affection than by ducal politics and Anthony Ulrich's persistent maneuvering. The joint coinage that followed documents a genuinely uneasy arrangement. Anthony Ulrich was the more ambitious of the two, later converting to Catholicism in 1710 to smooth his dynastic ambitions, a move that scandalized Protestant Lower Saxony.

The four-year window of jointly-attributed issues is narrow, ending with Rudolph August's death in 1704.