SNMP page counter; looking if duplexer is working

[Uwe Richter]

Hello all,
we want do page counting (where one sheet has
two inked pages) via SNMP.
Well, prtMarkerLifeCount (43.10.2.1.4.1.1)
gives a count, but if the duplexer is
set in action (HPLJ4100/JP610n), the number
of sheets are prtMarkerLifeCount/2.
So what SNMP OID may show me if the duplexer
is/was in action (e.g. by PS or PCL jobs).
Many thanks in advance
Uwe