I was in the same situation as you , i had sent a second application package for the same NOC , and i wrote an email to them to return back the second application as soon as i got the PER for my first one. And today i got my second package back -
Also mention the following details in the email
Full name,
Application Recieved Date
the courier tracking number,
passport number,
DOB,
Place of birth
Just to be on the safer side DO NOT mention your UCI from your first application in the email , who knows they might withdraw the one that has a PER instead .