At least one poster was able to convince a passport acceptance agent to accept two passport applications using the same naturalization certificate. I think he got the passports.
I asked at three post offices and each of them said "no, you need an original naturalization certificate for each application" so we applied for my daughter and my wife serially (one after the other). We actually got my daughter her passport first (she needed proof of citizenship about 1 month after my wife naturalized). My ceremony was about 5 months later.
You can try asking around. You may be able to do this if you can get to a "passport agency" run by the State Department.
N-600 applications only require a copy of the parent's natz cert, so they can be done in parallel with passport applications.
Good luck.
