Because it hasn’t been a copier in the sense you are likely thinking about - aka what we call today “xerox”.
It was simply a portable camera mounted on a boom with a light (or a built-in flash), used to photograph documents - either on a regular film or microfiche/microfilm. USSR made quite a few small cameras like that. They were commonly used for archiving official documents.
Likely a variant of this:
http://ussrphoto.com/wiki/default.asp?WikiCatID=17&ParentID=1&ContentID=1209
or this one which looks very similar to what is in the film:
http://ussrphoto.com/wiki/default.asp?WikiCatID=17&ParentID=1&ContentID=51&Item=Yolochka
