questions about my fingerprint experience

Dear all,
I am a july I485 filer, and got a fingerprint several days before in local INS office.
Interestingly, I only take a picture and sign it. I don't take fingerprint for all the
10 fingers. The code in my notice is 2. My question is that why I do not need to
do all the fingerprint as most guys did. Note that I have the experience for I485 before and it fails (I remember I have done all the fingerprint). This is my second I485 application.
I am asking if the previous records in the computer may speed up my namecheck and accelerate the approval my second I485?
Does anyone have experience on this?
Thanks for your response in advance.