I've recently reversed my Southampton to Croydon via Barnham as I noticed it's £60 p/a cheaper the other way!
Now it has been mentioned on the internet, expect the prices to be equalised (at the higher of the two values) at the next fares revision...
They don't even have to wait that long..."Obvious" mistakes (like the EMT bargains where they apparently forgot that fares are set in pence) can be corrected outside the normal fares round.