You can have several ways to have this happen.
1. you charge the khorne beserkers (they charged and go first) - after all chargers have fought you then start with a unit and pick the khorne beserkers again, and then alternate units till done.
2. you charge the khorne beserkers (they charged and go first) - after all chargers have fought you then start with another unit, and then alternate units till done. So the Khorne beserkers might end up after their opponent.
3. you kill your enemy with the khorne beserkers in their first round of fighting, they consolidate 3" towards then next closest enemy and might get stuck in again. But now it depends on wether you have declared a charge earlier versus that second unit.
a. no not declared: you cannot attack, but your opponent might if he didn't attack before
b. yes it was declared, fight again!!! (downside versus declaring against multiple targets is the possible suffering more overwatch)