Restarting Duplexed AFPDS Spool Does not Duplex

Basic Background: Printing an AFPDS spool file with multiple customer
invoices to Ethernet attached laser printer.  Sometimes necessary to restart
at a specific downstream page number in that spool file(paper jams, etc).
IP attached printer, Host Print Transform.

If re-starting a large spool file at a specific page number, duplexing
parameter on spool file is ignored.  It is there in the spool file
attribute, but simplex printing results.

If re-starting from page 1 of the spool file duplexing DOES work.

We were relying on the duplex(*yes) spool file parameter via CRTPRTF and
thought that perhaps the duplexing parameter used in this manner is somehow
conveyed in the first page of the spool file only?

So, we changed to DDS keyword DUPLEX(*YES) in the record format for the
first page of each invoice and still restarting beyond page 1 results in a
simplex printing.

We are running v5r1, v5r2 upgrade in a few weeks.  Researched/loaded PTFs
that might solve this(nothing specific found) with no improvement.

IPDS gotcha? Hope not.  Thus far this new process is running far better with
HPT than IPDS..

TIA...