That was something I have never understood from some devs, why put this dummys into the scene? To let the - otherwise lifeless place - appear more vivid? Really?! I'm sure a mannequin, or many, that stands useless around like in some kind of crrepy movie makes the scene waaay more busy...
Personally I would never put such a thing into a scene - a sure way to make a laughing stock out of myself. If I lack the computing power for such a scene would rewrite the scene to fit it for my hardware.
Luckyly, in this game this will never be the case.