You sent 2 to the NVC. As a precautionary matter, I like clients to bring 2 more when they go in to the interview, just in case.
This is not legal advice and a client attorney relationship is not created.
For consular processing through Ciudad Juarez it depends on your case number. If it starts with MEP, you should send a copy of two passport-size photographs and then bring the actual photographs to your interview. If your case number begins with CDJ, you need to send the actual photographs (2) along with the rest of your civil documents. There is no need to send two (2) photographs to the NVC and another two (2) to the Consulate. The NVC forwards your entire file to the Consulate at the appropriate time.
The advice given to you by my colleagues is correct.
Mr. Shusterman's (former INS Trial Attorney, 1976-82) response to your question is general in nature, as not all the facts are known to him. You should retain an attorney experienced in immigration law to review all the facts in your case in order to receive advice specific to your case. Mr. Shusterman's statement above does not create an attorney/client relationship.