Beck Arnley wheel hub and bearing replacement question

OK, has anybody here used the Beck Arnley hub assembly? I'm ready to put my new one on (old one is off). I noticed it came with 2 new o-rings. They are both the same size. They fit perfectly around the housing. The OEM unit only has the one. I'm probably overthinking this, but there is a concave circle at the base of the B/A unit, but the circle is larger in diameter than the o-rings.
Did I get sent a second o-ring by mistake? Old one is pictured as well.
I'm pretty confident I only need to use one.

 

I just replace my axles and hubs and there was only one O-ring there