In the Soviet Union and other communist countries the state security service would have samples of the print on all typewriters in the country. So they had the ability to track the typewriter if you would get an idea to write a flier or manuscript against the government. (In the movie 'The lives of others' they had a Stasi man who could identify all typewriters in east germany)

Now i thought that that was all due to the paranoid nature of Stalinism; it never appeared to me that western typewriters could also be identified by their type and that this was probably an intended feature, not just a bug. Now the same principle was later applied to laser printers ...