They are very similar, but no they should be different.

I have one of each in my garden and I find these (rather subtle) differences:
Oberon has a slightly smaller flower with a bit more of a greenish tinge than Pixie (hard to see if you only have one of them though!)
Oberon likes to grow upwards, Pixie trails - but then, knowing that, I didn't give Pixie anything to climb up so maybe that is not a helpful distinction?
Oberon in my garden flowers a whole 3 to 4 weeks later - late April to May whereas Pixie has been smothered in flowers from March and is all but done by late April.
Their foliage is pretty much identical as far as I can tell.
Only way to be sure would be to buy one of them from a reliable place like Taylors and wait for it to flower then you will know because you will either have two the same or two different ones. I prefer Pixie myself.