This paper argues that the Dutch sociolinguistic situation in the 17th and 18th centuries should be analyzed as diaglossic, that is, involving a wide spectrum of variation in between localized spoken dialects and the supposed written standard. In fact, multiple instances of norm selection for writing render this diaglossic situation even more complex. The paper shows that multiple norm selection even occurred in cases when a strict and simple norm was selected early on, that is, in the late 16th–early 17th century. The case study is based on the Letters as Loot Corpus comprising private letters from the 1660s–1670s and the 1770s–1780s and focuses on the object form of the 1st person singular personal pronoun, namely, mij or mijn . Despite the early selection of mij , some language users in the late 17th and 18th century adopted mijn in writing. The analysis shows a normative split in written Dutch of the time, with most language users either converging to or diverging from the supposed standard form mij .*