It is a published, well know information that morning flight DXB-LOS is on new 777 and the afternoon flight is old 340-300.
Having just broken locks on a Lagos flight you have to concider yourself lucky and there is nothing to do with EK. There are famous stories from the past of a BA aircraft being stoped on the taxiway and baggage compartments emptied by robbers. The pax just watched thru their windows how the bags disappear.
If you are not happy with your broken locks, complain at baggage service. I did it once and straight away been given brand new Delsey suitcase, matching my "brandless" suitcase with a broken lock