I just pm'ed you but for anyone else reading, I figured I would put an answer here too. Technically yes, only one original marriage certificate is needed for both the petitioner and beneficiary, but I got check-listed as they didn't bother to look at the opposite parent's case. Now if I was to submit that packet all over again, to be safe I would include a certified copy with each packet, so that they don't have to go looking. Chances are that you may have a different person that is reviewing each case number, especially if the case numbers are not numerically sequential.
are you filing on the basis of marriage to a u.s citizen?
If you are applying for naturalization on the basis of marriage to a U.S. citizen, send the following 4 items:
1. Evidence that your spouse has been a U.S. citizen for the last 3 years:
a. Birth certificate (if your spouse never lost citizenship since birth); or
b. Certificate of Naturalization; or
c. Certificate of Citizenship; or
d. The inside of the front cover and signature page of your spouse’s current U.S. passport; or
e. Form FS-240, Report of Birth Abroad of a Citizen of the United States of America; and
2. Your current marriage certificate; and
3. Proof of termination of all prior marriages of your spouse (divorce decree(s), annulment(s), or death certificate(s)); and
4. Documents referring to you and your spouse:
a. Tax returns, bank accounts, leases, mortgages, or birth certificates of children; or
b. Internal Revenue Service (IRS)-certified copies of the income tax forms that you both filed for the past 3 years; or
c. An IRS tax return transcript for the last 3 years.
so you're telling me you didn't send in anything regarding point 4?