Trying to print one page of a document in duplex - help!

Hi,

I've done a fair bit of work generating postscript from an OpenVMS COBOL system in the past, and while not an expert, have usually managed to produce something that works. This time I'm failing. Can anyone assist.

The problem: I have a document which has to print from 2 trays.

Tray 1: (Headed paper with blank background)

Tray 2: (Special paper with writing on the back)

Up to now it has been a simple simplex job, printing one page on headed paper and then page 2 (and more) on the special paper

<< /MediaPosition 0 >> setpagedevice

(PAGE 1) show

showpage

<< /MediaPosition 1 >> setpagedevice

(PAGE 2) show

showpage

I have to add a sheet printed on both sides between page 1 and page 2  (A) on the headed side and (B) on the blank reverse.

I tried

<< /MediaPosition 0 >> setpagedevice

(PAGE 1) show

showpage

<< /MediaPosition 0 /Duplex true >> setpage

(PAGE A) show

showpage

(PAGE B) show

showpage

<< /MediaPosition 1 /Duplex false>> setpagedevice

(PAGE 2) show

showpage

This produced page 1 on headed, page B on headed with page A upside down on rear. then page 2 on special paper.

I can get A to be the right way up by changing to

<< /MediaPosition 0 >> setpagedevice

(PAGE 1) show

showpage

<< /MediaPosition 0 /Duplex true /Tumble false>> setpage

(PAGE A) show

showpage

(PAGE B) show

showpage

<< /MediaPosition 1 /Duplex false>> setpagedevice

(PAGE 2) show

showpage

but still I get page B on the front and A on the back.

if I reverse thus:

<< /MediaPosition 0 >> setpagedevice

(PAGE 1) show

showpage

<< /MediaPosition 0 /Duplex true /Tumble false>> setpage

(PAGE B) show

showpage

(PAGE A) show

showpage

<< /MediaPosition 1 /Duplex false>> setpagedevice

(PAGE 2) show

showpage

I get A on the headed side, but upside down, and B on the back (also upside down)  and B is stacked first so someone looking at it will see 1 B(upside down) A(upside down on headed), 2

I just want  1 (headed)  A (headed), B (reverse of headed), 2 (special)

Can anyone suggest the solution (to an HP Laserjet or 5550dfn if it helps)