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Hillary Clinton refused to concede on election night.
See: https://www.ap.org/the-definitive-source/behind-the-news/cal...
See: https://apnews.com/article/fb2e92a47f054019a2589ace78d20836
Based on the former link, Hillary gave her concession call to Trump at 2:50 AM EST.
She gave her public concession speech several hours later.
See: https://www.politico.com/story/2016/11/clinton-concedes-to-t...
I'm rather curious what more you expected.
In Gore's case, we had a razor thin electoral result that hinged on a single state with less than a 550 vote margin against 5.96 million votes cast, or 0.009%. We can argue about how many recounts there should have been, but it makes perfect sense there'd be some contention when the entire election came down to so few votes.
To his credit, he conceded the day after the Supreme Court made their ruling, exhausting his final legal recourse.
See: https://www.theguardian.com/world/2000/dec/14/uselections200...
You may notice a distinct absence of attacks on the US capitol during the certification of either the 2000 or 2016 elections. You'll also do well to note that Bill Clinton in 2000 and Obama in 2016 dutifully aided their Republican successors getting up to speed with their office on the way in, sharply contrasting Trump's treatment of Biden's incoming administration.
And, to this day, Trump still hasn't publicly conceded his 2020 loss. Quite the opposite - on multiple occasions, he's voiced the opinion that he should be allowed to run again in 2028 to make up for his "stolen" second term.
There are still plenty of Republican members of Congress as well as many state-level Republicans who maintain the 2020 election was stolen.
You would have a hard time finding a single elected Democrat at either the federal or state level who would claim any presidential elections were stolen from their party's candidates.
There is no good faith argument to be made that both parties are the same in this regard.