Submitting a form as flattened

[CBV IT]

I have created fillable office supply request form using Nitro Pro 11.0.3.134, and set up a button to submit the form an email recipient who fulfills the request and passes the file on to our controller for proper billing.  The all works fine; however, our controller is trying to take each separate file (let's say 5 different pdfs) and combine them into one using Nitro Pro.  When Nitro combines the files, instead of adding each of the 5 document as a new page, it duplicates the first document 5 times.

This only seems to happen on these fillable forms.  Any other documents combined seem to work OK.  So my assumption is that something in the fillable form.  I know I (with Nitro Pro) can save the completed PDF as flattened, BUT is there a way to modify the form so that it is submitted as flattened.

Any help would be greatly appreciated!