Regina Regina:
I'm pretty sure it will be the same in this case too. By charging both, the guilty one my man up and take the punishment. DNA also says it was both of them too. Which again may force one of them to prove it was the other in court.
Burden of proof is on the prosecution to prove who did it, not on the defendants. If the Crown has nothing more than "It's one of these guys" then they'll both walk.