So we were running FoS1...And after the first boss this happened. ------------------ Also to be noted is that we fought the boss and he was, as usual, trapped a bit so we had to back off to let him activate the cutscene. Thing is the cutscene started going crazy. Flickering like crazy. That's when we noticed the clones. I figure that by blocking him when he was normally trying to activate the cutscene caused it to treat it as activating the cutscene multiple times (Hence the flickering and clones)
the fortress is built in a spot where the walls between parallel dimensions are weak letting us glimpse into them.