Tech Question: Allowed to play green games and beat the jackpot score?

I get that the employees are there all day, and I'm sure get extremely bored during down times. But, for weeks, we started arriving to jackpot scores that were far higher than the base scores that they were in the past. So, okay, we have competition from other gamers, fine. Or, so we thought. Then, we started to notice that when certain employees were working, the scores would be higher. Then, we witnessed it for ourselves. For a couple of weeks, we've seen the same few employees beating the jackpots of Tailgate Toss, Quick Drop, and some others, almost scalping the jackpots when they get high enough to be easily beat or have scores low enough to win.

So, is this standard practice and permitted for employees? It seems it takes away the chance for a jackpot for most players.