If aliens landed and had the same scripture as our bible, you could assume they obtained a copy when they first visited, or that someone who had a copy visited them. This wouldn�t prove anything other than other life forms exist(ed) and travelling to them is possible, which would be obvious anyway as we would be staring at a couple of aliens.
Likewise if someone from some far off galaxy (from earth) turned up at their planet with a copy of the bible, then they would likely be sceptical of anything they said like we would be if they turned up here. They would be more amazed at a strange being carrying some papyrus, rather than some stories about a man who was jolly nice, and did some good stuff and then the romans killed him.
Is that proof of God�s or Jesus� existence? No. Just that somebody somewhere knows how to travel a very long way through space, and we ought to learn their secret.
I think I know where you are coming from sheman, although it appears you have been needlessly taunted for daring to ask a�. question.