Happens pretty often. Burdens of proof for each charge is separate. As said below, he can still be convicted of lesser charges. It's not double jeopardy to have all those charges. It would be double jeopardy to have to trials under the same exact charges.I had the same question. My best guess is that if they charge him with all three, it allows a jury to pick which one to say he's guilty of. It's not double jeopardy unless they were to find him guilty of more than one of them. If they were to only charge him with the second degree and the jury found that the evidence didn't rise to the standard, then he's acquitted and they are unable to bring another round of charges.
Personally I would say it's BS. The charge should match what they think they can get a conviction for.