This Noctis hasn't the slightest clue what his other self encountered or did during the mission, but he's sure enough that copious amounts of sleep will help a lot, so he'd agree with going right back to sleep.

That said, he had no idea who was even nearby and didn't think much of it as he mumbled a quick 'scuse me' after misjudging the distance between them and bumping the other Noctis' arm as he passed. But then the other man spoke up in his voice and he stops in his tracks.

He'd wanted to meet one of his other selves for a while. There'd been one on the train before, and one in the Drift Fleet, but he'd never interacted with either of them to any great extent. He had a pretty good idea why, thinking about it right now.

How do you greet yourself?

"What? I didn't bump you that hard." Nailed it.