I have a similar question in regards to OneWorld mileage award.

I'm flying from Syd-Europe roundtrip and according to the WebFlyer mileage calculator the trip should come under 10,000 miles each way. However, for some reason AAdvantage desk keeps telling me that the total mileage is in excess of 23,000 miles. Any ideas? Can I do something about it? It's a pity to throw away an extra 50,000 points for no good reason.

Also, I have a forced stopover on my return leg. Could this somehow affect the total mileage?