Sorry I don't know the exact answer to your question, but you can click the "Fastlane" link at the top of this page and shop for the parts - cheap, quick and OE quality, too! That should tell you if there are two O2 sensors.
Also, don't forget to try the Search, you will get answers instantly!
RIP "Betsy" (Oo=*=oO)
'96 E 3 2 0 (W 2 1 0) M 1 0 4 (Totalled)
Spaces in sig so as not to screw up the SEARCH; every time someone searches for that MB they don't want my sig!
2004 Audi A8L
'98 VW Passat 1.8T 5M
'87 Alfa Romeo Milano 2.5L 5M
'67 Impala convertible, 327cid