It's simply coincidence, though both makers have expressed overlapping reasons to make their film right now, in particular the rise of the extreme right.
Also note that while both films ostensibly are about the same event, they are significantly different in tone and execution.
Both directors have talked about what drove them to make their movies, here are some selected interviews:
Erik Poppe to Nordisk Film & TV Fond:
Nordisk Film & TV Fond: Why did you decide to bring the highly sensitive subject of the Utøya
massacre to the screens and why now?
Erik Poppe: Basically, back
home, there has been a lot of discussions on various aspects of July
22, 2011, technical matters like the reconstruction of the government
building in Oslo that was destroyed, where to have the victims
memorial, and the perpetrator of the massacre has taken many
opportunities to get media attention, by complaining about his life in
This has taken the focus away from what really happened that day. We
need to get the ownership of these events back to the victims.
Therefore I wanted to tell the story from the point of view of the
youngsters who survived, and the relatives. Some people have said it’s
too early to show it, but others said: when is the right time then? If
we wait for everyone to agree, it will be too late!
Another important aspect is the way neo-fascism has gained supporters
across Europe over recent years. I believe it’s really important to
show that this massacre has happened and can happen again. We need to
be reminded of it to stand up against it. As a filmmaker, an artist,
it’s my task to bring up this subject that concerns me and should
concern many of us.
Paul Greengrass to Uproxx:
Uproxx: The first 30 minutes of this movie, the attacks, are just so
Paul Greengrass: No, I get it. I get it. I had to think about all that before I made
the movie. What I would say is that it’s not a film about the attacks,
it’s a film about what happened after.
Uproxx: But you have to still show what happens, I understand that, but it’s
Paul Greengrass: You have to go through that experience in order to tell the story of
how Norway fought for their democracy.
Uproxx: Is it about Norway fighting for its democracy, or is it about what’s
happening in the world today?
Paul Greengrass: Definitely. You’re bang on the money. A reason I made the film, we’re
facing a massive right-wing and unprecedented move to the right.
Paul Greengrass to The Atlantic:
What clinched Breivik as a subject, Greengrass told me over tea in
London recently, was the moment he read the killer’s court testimony.
“That was extraordinary,” Greengrass said. “He talks about the
betrayal by the elites, the sham of democracy, enforced
multiculturalism,” he continued. “Those opinions in 2011, 2012, would
have been considered on the margins of discourse. Today, what he said,
that’s mainstream now, that’s populist right-wing rhetoric.” Not his
murderous methods, “of course not,” Greengrass said; “I’ve no doubt
that Steve Bannon would abhor Breivik’s methods.” But that’s not the
point, he said. “The point is the worldview, the intellectual
framework, if you can call it that, is the same and it has moved into
Greengrass has always been drawn to political subjects. Earlier in his
career, he made two films about the troubles in Ireland, Bloody Sunday
(2002) and Omagh (2004). His United 93 (2006), about the plane whose
passengers took on their hijackers after learning about the World
Trade Center attacks, causing the plane to crash into a field in
Pennsylvania and not its target, may be the definitive film of 9/11.
And the three movies about the rogue CIA agent Jason Bourne that
Greengrass is best known for directing are about the guilty conscience
and emotional toll of American covert power. His 2013 film Captain
Phillips, about the hijacking of the Maersk Alabama by Somali pirates
in 2009, examines the unlikely profiteers from an impoverished country
trying to get their slice of the global economy. Now, with 22 July,
Greengrass has definitely secured his place as the auteur of
globalization and its discontents.
These questions were very much on the director’s mind in the fall of
2016—after Brexit and before the election of Donald Trump—when
Greengrass said he first started conceiving of the Breivik film. At
the time, he’d actually set out to make a film about Lampedusa, the
Italian island that was for years the first port of arrival for
hundreds of thousands of migrants coming north from Africa into
Europe. “But the more I sort of set out to do it, the more I felt that
that was, for all its humanitarian tragedy and personal drama, that it
was only a piece of a much larger story,” Greengrass said. “And the
larger story was about the projection of globalism.” He sees 22 July
as a kind of bookend to United 93. If United 93 “was really about
blindness,” he said, “that we were blind and they were blind”—we being
the targets and they the terrorists—then 22 July looks at a different
kind of “rejection of a globalized vision of the world,” he said. The
way Greengrass sees it, Breivik is an “original member of the
‘alt-right,’” which grew up in the wake of 9/11, he said.