Greek mythology

In the iliad it says that Diomedes killed Aeneas. then in the Aeneid Aneas leads the trojan out of troy. how is this possible?

Pandaros and Aeneas tried to attack Diomedes. Pandaros got killed and Aeneas did not.
Diomedes didn't kill Aeneas. Diomedes gave him a grave injury by striking him with a rock, but Aphrodite, Aeneas' mother, saved him from his death.

Wats with people striking eachother with rocks? Why can't they just be friends?