They shouldn't have been near each other. Lando was given the preferential undercut strategy despite being behind on track. Oscar had a slower stop and still almost stayed ahead. If Oscar was pitted first like you would hope they don't end up next to each other at T1.
I totally understand Piastri trying to put himself in front in the situation. F1 is so unfrogiving towards rookies and drivers in general. If Piastri would let Norris pass everytime just because Norris is the #1 driver, many teams would dismiss him as potential #1 driver in the future because "he lacks the fighting spirit". Given his recent performance there is no doubt he will get a new contract somewhere even if he were to fall out with McLaren. So he only stands to lose by staying too passive.
If McLaren followed their own philosphy of "The Team above all" they would have pitted Piastri first. There was no reason to pit Norris first. They didn't have to protect against an undercut from someone else. And if Norris actually were faster and held up by Piastri the undercut would have worked.
On lap 24 of 51, the McLaren pair came to blows at the first chicane as rookie racer Piastri re-joined the Monza track alongside earlier-stopping Norris in a dice for what was then 10th position.
With Piastri on the inside at the tight first apex, the front-right of the Australian’s MCL60 glanced his team-mate's sidepod. There was no major damage and both escaped punishment from the stewards.
Nevertheless, team boss Stella branded the incident as “unacceptable”. He said: “There should never ever be contact between two McLaren cars.
“There was a contact, which doesn’t fit the way we go racing at McLaren.
…while we were watching two Ferrari fighting each other towards the end, and everyone was asking himself whether they would shoot each other off the track…