These are Koudelka's early works - before the Prague Invasion and before his "Gypsies" set. The first two are photos taken during rehearsals at the Behind the Gate theater in Prague - mid-60s, he hadn't even switched totally to being a photographer then, was still working as an aeronautical engineer. So you have a combination of theater lighting, with its extremely high contrast, and (probably) slow film.
Not sure if he had access to very sophisticated film. The major work, though, to achieve the look - for those and for the street photos -, was done in the darkroom, in which he spent hours experimenting.
It would be misleading to call this part of his "style" - he fully became a documentary photographer after the Prague Invasion -, but it certainly taught him about light, contrast and the ambiguities they can created when well manipulated within the photo documentary context.