What was the reason why 9M-MRO burned more fuel on one engine?
Those engines all look the same to me.

1.5T per/hour difference does seem excessive, but probably not unheard of.  It could be just because one engine is newer than the other and has less wear on it.

If you look at APPENDIX 1.6B of that same report it shows that the right engine consumed about 1.5% more fuel during Takeoff and Climb, not 1.5T more, so it may just be a typo. 

(APPENDIX 1.6B WF is fuel flow in lbs/hr)




Here are some crops of the photos you linked to:


Jan. 15, 2012 




Feb. 16, 2013




Oct. 28,2013




Jan. 22, 2014




Feb. 8, 2014




Feb. 10, 2014