eyeinthesky,
Okay, I didnt RTFQ.
Sensible answers are as VP says it could have two different phase engines. (At least one TCX aircraft has this).
Other possibility is, both engines are identical, but of course are mounted at different angles to the horizontal due to dihedral. The net result is it is not unsual to see an aircraft with less oil qty in the left than the right.
Whilts this may be the answer, I'm not overly convincing myself, didnt think it'd be that obvious on t/o. Have seen it smoking on the ground after shutdown though, particularly if it had been recently topped up.