Are there examples of crystals with random but static mixtures of two unit cell configurations?
Possibly retracted soon, because I'm not aware how to include a picture in a comment to clarity your question.  Do you mean instances like the following, where sites seemingly are occupied by two atoms simultanously -- as in analogues of Prussian blue -- just because the model deposit in the .cif is the average of the unit cells' content?



(Chen et al. in Angewandte Chemie,  129, June 2017, 9151-9156, doi 10.1002/ange.201702955)