I got both the front and rear o2 sensor (i won the bid on ebay, and it came with both)

Both look identical

are they both the same one?
and if so, it doesn't matter which is installed where?

 

Well on my car the one that goe into the header plugs up in the engine bay somewhere and the one going to the cat has wires going up into the car so without a picture i cant really help you...hope this little bit of info helped