And then Voyager did "Work Force" 2 parter and SG-1 came out with "Beneath the Ice" which had ice in it which made it legally distinct.
Although IIRC both were based on a sci-fi short story or some such.
Actually, SG-1's "BENEATH THE SURFACE" aired in September of 2000 and VOY's "WORKFORCE" aired in February of 2001, so SG-1 really did it first.
As others have mentioned, there are a number of episodes that are
very similar... some to the point of being virtually identical. (VOY's "ONE" and ENT's "DOCTOR'S ORDERS" is a perfect example of this.) However, there are enough subtle differences to make the episodes still interesting.
Take
"EX POST FACTO" from VOY, for example. While on the surface it seems similar to TNG's
"A Matter of Perspective", there are more differences than similarities. The TNG episode was ultimately showing how easily perspective and narrative changes with each person, even though events are exactly the same. The VOY episode was more a noir murder mystery that brought a unique punishment for the crime. (Plus it had an interesting throwaway piece of dialogue when the magistrate said, "An artificial lifeform testifies to the memory." Or words to that effect. Makes me wonder how prevalent androids or other artificial lifeforms are in that society.)
I can't really fault the franchise for reusing a plot point because after almost 60 years, 11 shows, and about 900 episodes, there's going to be a fair amount of reused plots. (Even in other franchises, like STARGATE, ANDROMEDA, BABYLON 5, and FARSCAPE, you'll see reused plots from other franchises being used frequently.)
What I do look for is how interesting the current episode or movie I am watching is. A plot from a previously bad episode might be a good version of the current one I am watching, and vice versa. The characters are the real differing point. Even a different setting is not as important as the characters are, because I'll be more invested in
them.
