Adjustment of Status - I-485

During my EB2 interview, the IO realized that my file contained documents from both current EB2 and a prior Denied EB1 ( its I140 denied, but its I485 never been formally denied). Apparently NBC merged all document - may be thinking it is all one EB application. Furthermore we noticed that the receipt number used to call for my Interview was associated with the denied EB1. The IO was able to understand the issue and started separating both files. Then he carried out the Interview with the correct EB2 documentations associated with the approved I140. Interview went well, and the IO mentioned everything is ok but he will need to send my case back to NBC for further background check. Indeed few days I got the update my file transferred to NBC. Not knowing how the IO cleared the mix up of the the 2 applications, I am worries that NBC could look at the wrong denied I40 (from EB1), and deny my I-485 as they may not realize there are 2 applications. Could you please advise if this scenario could happen, or somehow NBC have a system to ensure the correct I485 is tied to the correct approved (EB2) I-140 files together? Thanks