system
Given the following post, respond as if you're commenting on Reddit:
human
[40K] Our ship is too fast, please help.

So I have the honor of serving on a Rogue Trader's ship, big family legacy. Okay, so a few weeks ago we arrived at a system over a week ahead of ourselves. No problem, it happens, especially when our ship is so fast thanks to our xenote... endless faith in the Emporer. However, then after the next jump we ran into Big green problems and had to run back to the previous system so fast we arrived before we even left the first time, burning out our engines.

A guy I know works on the bridge and overheard that we're going to meet ourselves in about 2 days and the engines won't be ready for a while.

So what's going to happen? Is no one going to show up? Are we going to not exist anymore? We lost like 80% of the crew to the Green Backs, can we just warn the past ship to not make the next jump and go somewhere else? I liked some of those guys, and we lost like all of the decent looking women and for the sake of argument all of the Inquisitorial spies on board.
gpt
The Warp is a strange place, and while it is incredibly rare, it is not totally unheard of to reach a destination before you left, at least as far as the "timeline" is concerned. Yes, there may now be two versions of you in the same Universe, but "their" existence no longer has any bearing on your existence. 

We know of Warlord Grizgutz who managed to travel back to his own homeworld before he had left in the first place, decided that the other him was unworthy, and so killed himself to have two of his favorite gun. When this happened, Grizguts did not disappear. He didn't cease to exist. He simply went on being his Orky self, albeit with two of his favorite gun. 

The fact that you got somewhere before you left means nothing. The "other you" will still head out just as you had already done, and who knows where you'll end up. See, the Warp isn't linear when it comes to time. Just because YOU went back in time doesn't mean that the other you will. There's no causality. Maybe they'll get exactly where they wanted to go, exactly when they wanted to get there. Maybe they won't pop out for another 300 years. Maybe they'll never be seen again. What matters is that YOU are okay and can continue in the Emperor's glorious name.