Resolving MailStream Plus 8.3.0 will only let you select either the Mail.dat PDR file (Piece Detail Record) *or* the PBC (Piece Barcode Record), not both.

Yes, the USPS only wants one of those files to be included in a Mail.dat fileset.  

Which one you want to produce is determined by REPORT MAILDAT position 36 and 39.  MailStream Plus defaults to producing the PDR file (position 36) and not producing the PBC file (position 39.)
UPDATED:  April 14, 2017