Maybe the early TNG 2360s jumpsuits were that time's equivalent of the DS9/VOY jumpsuits with the coloured shoulderpads. A less formal uniform variant, as opposed to the formality of the TWOK uniforms. They may have served alongside the TWOK uniforms for a while. And eventually the Wrath of Khan ones were phased out.
In Generations, we saw a bit of a mix and match of uniforms. The TNG season 3-7 ones, and the DS9/VOY jumpsuits. Some characters switched from the TNG style ones to the DS9 ones mid movie, notably Data, Picard, and Riker.
It's possible that a similar mix and match was going on aboard the Stargazer. With TWOK uniforms appearing alongside the S1-2 spandex jumpsuits.