I thought I already posted this butm these guys are all nuts.
That is NOT a dual capstan deck, it has two capstans to facilitate reverse play. they are not both active at the same time, How could they be ? They c an't. Unless you stick that pinch roller inside the cassette and... fukit, they tried that with eight tracks. Plus it wouldn't fit.
Only one capstan is active at a time, that is when the pinch roller is enga ged. both capstans turn in opposite directions all the time but it doesn't mean shit until the pinch roller hits the tape. If both ever hit at the sam e time the deck would come to a screeching halt, LITERALLY.
Look at it more closely and you will see.