Al Gore disputed the outcome of a single state where he lost by a few hundred votes. He did not dispute the outcome of the entire electoral process or make baseless claims that it was rigged for months leading up to and after the election.
I didn't recall the date though, I checked and it was on December 13th, 2000.
Come back on 14 December 2020 and tell me if that aspect is "exactly this".
because the narrow vote count margin aspect that time really isn't, and the claims of fraud and rigging this time really isn't. And neither bode well for a hypothetical Trump concession speech.
"does not attempt to dispute the outcomes of elections when the results are clear"
In 2000 the results were not clear. This year they are.
Furthermore, once the Supreme Court shut down the Florida recount, effectively handing the White House to George Bush (on very questionable legal grounds [1]), Al Gore conceded.
Al Gore never claimed that he was the only legitimate winner months before the election began and that any result in which he lost would be fraudulent.
You may not be old enough to remember, but Al Gore (democrat) did _exactly_ this 20 years ago.