It's pretty clear that in 1982, while they were trying (and failing) to sell many Iron Maidens or Orbitor 1s, Stern was working on their next game, LazerLord. They were building up a whitewood in a leftover Viper cabinet (a completely normal series of events), and had already gotten sample backglasses produced.
In the November 1982 Replay Magazine, on page 37, is an article headlined "Stern Shuttles To The Suburbs" detailing how they were selling their Diversey Pkwy building, and had consolidated all operations in their URL subsidiary's building in Elk Grove. It includes a line that starts "Stern has ceased all pinball manufacturing..." I believe that's just when they made it official, by not setting up a pinball production line in Elk Grove, but the decision had been made months earlier... thus the last date of June on the whitewood's ROM labels.
I don't have at hand my late-1984 Replay Magazines, but in early 1984 they were clearly on the downswing, with their VP resigning in April, and a May story detailing the sale of the Seeburg assets in March. In the March 1985 issue on page 18 is an article titled "Stern Liquidates, But Gary Stern Opens Carrin Electronics"
Stern absolutely showed a game called "LazerLord" at a trade show. That was the reason for the existence of the flyer (which you can see in the link for the game on IPDB.) The flyer uses the tagline "Pinball Is Back!!!" and has their Elk Grove Village address, along with a crappy photo that clearly matches the complete-with-artwork narrow body version of the game. While I don't have the issue of Replay with a report on the fall 1984 trade show to prove it, I think it's pretty obvious from the clues that's when it was.
So the theory that, in a desperate move as the company was faltering, Stern tried to release a pinball using existing parts (their stash of LazerLord glasses, and the already-engineered Quicksilver design), would seem to be correct.
So this explains the two dates.
1982 is when they were developing the game, and probably would have released it later that year if they hadn't exited the pinball business.
1984 is when they tried to sell a game by re-using existing parts, but a game that required no engineering, because they had no pinball designers on staff by that point.
They are two totally different games. The 1982 whitewood was the original LazerLord idea by Joe Joos, the 1984 game is just a reused game design, with the LazerLord art package applied to it.
Anyone who has ready access to late-1984 Replay or PlayMeter Magazines, who can nail down that last little bit of proof on this? I'll eventually find it if nobody else does, but my copies of those magazines are in storage elsewhere at the moment.