If my GRE score decreases, will the school I already sent the score know?

<p>I just took my 2nd GRE yesterday, and my score decreased, so I didn't choose to send that score to any school. Will the school that I sent my 1st GRE score know that my 2nd GRE score decreased? If on the application there are 2 slots to put in GRE scores, can I not put in my 2nd one as well and put in only the 1st one?</p>