The nuns of the vayehi binsoa section have not always been separate as this scan of a 700 year old scroll, hanging in the office if the UK’s no. 1 scribe, shows. The first nun is in binsoa and is backwards whilst the second is in the word k’miton’nim (as murmerers) in the following pasuk (sentence). However there is even debate here and some opinions were that the second nun was in u’v’nucha (and when it rested) and some even said there should be three, as this might be the intention of the Zohar (Mishnat Avraham). The nuns themselves in this instance are highly decorated with taggin and swirls above and below in kabbalistic style as per Sefer Taggin.
(with thanks to the late Vivian Solomon for the scan)