Not sure how well known this reference is but...
The two Maries from Daisies (1966) also crop up in a cameo appearance of another film, Mucednici lasky (1967)
Mucednici lasky was an anthology film also in the Czech New Wave film movement (of which Daisies was also a part of) and the characters of the Maries are seen in a cameo in the first segment.
Interestingly this segment takes place in a jazz club, and the fact the singing is similar might be a reference to the silent jazz club scene in Daisies.
As the Maries's cameos in this film are not written by the writers of Daisies, they seem a bit annoying here. Then again this scene is from the viewpoint of society...
You can see this via a brief clip on youtube.
