Venkmans pack rotated counterclockwise in both films....... So you say it was an error
Yes, I say it's an error.
The first film is pretty consistent when it comes to which actor has which Pack with which light movement, with Murray being seen pretty much exclusively to be wearing the Pack with the reversed pattern (except, when they blast Mr. Stay Puft). In Ghostbusters II
, it's counter-clockwise in the Courtroom, and some moments of the battle with Vigo, while other moments of that battle, and while they're piloting the Statue of Liberty feature a Pack whose lights move clockwise.
The fact Murray ends up with that unique Pack so often is simple to explain when it's been noted several of the props had nametags applied to them... Either on the motherboard or on the lowest part of the A.L.I.C.E. Pack frame. From that, we can reason Murray just happened to be given one with a different lighting pattern, and kept getting it for a majority of his scenes because it was the one with his name on it. Instances where the pattern is seen rotating clockwise are the result of him either having been given the wrong prop by a stage hand, or a lighter GBII Semi-Hero over the heavier GBI Heroes.
In-universe, there's no explanation for the change in lighting - it's not a function of the Packs being fired because nothing similar happens with Dan and Harold's Proton Packs. We can also rule it out as some sort of intentional design element from the in-universe standpoint because it appears inconsistent.
The simplest explanation is the most likely one (Occam's Razor) - Two of the GBI Packs either weren't wired correctly (or more likely, had the switch/switches flipped the opposite way to the other two), and nobody corrected it. The error persists to the filming of Ghostbusters II
because some of the Packs props from the first film were reused, and Murray ended up with the same one because his name was applied to it.
Why would they go to the effort to make the four main Proton Pack props look visually identical, only to then make a couple of them light up differently from the other two?
It's not a stretch when we look at the other inconsistencies and damage that they gear picked up because they're manhandled props: Ghost Trap doors hanging open, missing cosmetic plates exposing internal wiring, scuffs, scrapes, peeling labels and mysterious elements that are only seen for one brief scene and are never seen again (And that's not even digging into the visible wear and tear in Ghostbusters II