ASK AGAIN, Please XBT and Radiology etc. help me clear this. THX

I just received my 2nd fingerprint notice from NSC. 1st fingerprint was done in September 2005. I am depedent and my LG hasn't received the 2nd fingerprint notice yet. Strangely, I received two same notices with the same appointment time at the same time. I don't know why USCIS duplicated the notice to me while my LG as principal applicant hasn't received even one. Does that mean USCIS mistakenly sent me my LG's notice? Should my LG just wait or call USCIS?
Thank you in advance.