MIAMI – Erik Spoelstra sat with a paper cup holding some undefined celebratory drink — “Don’t worry about it,” the Heat coach said, smiling — when outside the closed door of his news conference, unheard by him, a sudden, staccato cheer burst from some fans in an arena hallway.

This is how the second gust of good news arrived late Friday night. The Florida Panthers had just won in overtime in Toronto. They closed their second-round series 20 minutes after the Heat had closed their series and now advanced to their Eastern Conference finals just like the Heat did, too.

You know those movies where someone relives some miserable day from their life, trying and trying to get it perfectly right with each reliving? Friday was the day when it’s perfectly right. It was an overlapping ode to sports joy that’s never happened for South Florida — or probably any market.

Gimme whatever Spoelstra’s having.

Raise a toast, South Florida, and savor the taste because Friday was the best day in our sports history that didn’t result in a championship. It doubled the fun, squared the celebration and was a surprise stacked on a surprise considering each backstory.

These no-good, eighth-seeded, doppelganging Heat and Panthers advanced almost simultaneously to their respective conference finals?

“Spectacular,” Spoelstra said after his 96-92 win against the Knicks when told the Panthers had won in overtime, 3-2.

They’re unidentical twins, these two teams in their separate seasons. Think of muscled Arnold Schwarzenegger and miniature Danny DeVito in “Twins.”

You know which franchise is Schwarzenegger. The Heat have won three championships. They’ve been to three other NBA Finals. This is their third trip to the Eastern Conference finals in four years and their 10th overall as a franchise.

The Panthers are DeVito. They hadn’t won a playoff series for a quarter-century until last year. They hadn’t even hosted a Game 6 in their arena until the previous series against Boston. This is their second Eastern Conference finals — and first since the lone shining yesteryear of 1996.

Look at the similarities to these seasons. Both teams struggled in the regular season. Both made the playoffs by the hair of their chinny-chin-chin. Both went against the top-rated team in their league in the opening series. Both defeated iconic brands in the second round.

Each home arena mobilized for these recent series, too. It wasn’t just the expected noise. Consider the cheeky chants.

“We want Florida!” Panthers fans chanted after going up 3-0 to mock Toronto fans, who earnestly chanted that in hopes of getting Florida instead of perceived heavyweight Boston.

“Refs you suck!” Heat fans chanted Friday in what’s usually a tired and tedious message. But this one came in the opening minutes of Game 6 and resulted from fans knowing the league had assigned head referee Scott Foster to the game.

It’s a slippery slope to overstate officiating. But the Heat were on an 0-10 run in games Foster refereed, and he was assigned to Game 6. Coincidence?

The Knicks made more free throws (11) in the first quarter than any opponent had against the Heat all season. They were in the bonus with just under 10 minutes left in the fourth quarter, a potential death knell considering any Heat foul resulted in Knicks foul shots to the end.

But Foster is now 1-10 in his past 11 against the Heat. And those Toronto fans? They left into a bitterly cold spring after a series-ending goal by the Panthers’ Nick Cousins just as Spoelstra was settling into his postgame news conference.

Cousins fits with the Heat story. Oh, each team has risen stars like the Heat’s Jimmy Butler and Panthers’ Matthew Tkachuk. They got hero games Friday from big names like Bam Adebayo (23 points, nine rebounds) and goalie Sergei Bobrovsky (50 saves).

But Cousins is a journeyman on his sixth team who played on the Panthers’ fourth line for most of the season. The Heat is full of undrafted players like Max Strus, Caleb Martin, Duncan Robinson and Gabe Vincent, who was told at his locker late Friday night the Panthers had won.

“What?” he said. “They won, too?”

Vincent attended the Panthers’ opening game during the Toronto series.

“My first hockey game,” he said. “I learned all about icing and offsides. I still don’t understand how they change players all the time.”

And then Vincent, at the end of this unmatched day, capped it with the right cheer.

“Go us,” he said

Raise a paper cup.