Thanks - the back on the Jennings/Jordan is P350, I own that one:
link
I have the Engle/Phillippe listed with the Engle on the bottom, Phillippe on top.
I also have 4 side by side possibilities listed, based on scans I've seen (left/right):
Fletcher/Charles
Sheckard, no glove/Goode
Schirm/Mullin portrait
Willett/LaPorte
Any others known like that?
Tom