Zirkzee can be the chosen one to stay at the club but I see no reason to keep both players because with the two players combined they couldn't give up to 20 goals and their performance wasn't something to write home about. The manager can give Zirkzee a chance to redeem himself only on FA Cup or Carabao and also for him to be a back up striker that's if they sub Benjamin Šeško or if he has any form of injury.
Zirkzee will stay from the news we have been seeing but we what I have seen in their last game I can't imagine Zirkzee keeping up to the speed at which Mbeumo and Cunha are bringing to the team, UTD need someone who can keep up that style of play and Zirkzee or the other one Hojlund isn't the type, is best if the manager get someone to replace both players, maybe do a swap to get a better striker to support Benjamin.
Judging from Rasmus hojlund performance after the preseason games he has really improved in Manny way and he was quite a good finisher in the preseason games so I would suggest they give him a little time to prove himself once again at least a second chance is needed but don't really think Manchester United bored and fans will be that patience judging from his last season performance too, so in my own opinion think Rasmus hojlund should leave the team, for Joshua zirkzee he's still a promising young talent and should be given the chance, he hasn't got enough time to do his things and the few he has done he was quite good at it so he should stay.
Rasmus need more time like a second chance no doubt but I feel that the time he had with the team was enough not now that they Red Devils have a new striker that he'll do well. Amorim is some how working on borrowed time to make this team better and he doesn't need any player to remind him of how weak his team was as of last season, he need something different and I feel he is getting that positive vibe with the players he is working with.
The way Rasmus Hojlund and Zirkzee played last season was terrible, it was as it UTD never had any attacker which is true, you can't tell when they'll turn up and be more productive, the competition was between the both of them so I see no reason to even keep any of them, the highest that can happen is dropping one and letting the other one go on loan or sell him completely because the squad we are seeing now can do better compared to that of last season without them.