Though you can never be too sure, I dug around a bit and I think what you have as far as a code is legit. The diplos were made as a cheaper alternative to the Monte line and were made along side of the Montecristo brand, a different blend but similar sizes and made in several different factories.
On another note, the last three codes for the El Laguito factory were:
EL
EUN
LOME(newest) I couldn't find a code note for El Laguito as ECA, do you know when this one was put into use lalolemus? Anyway, if you want me to sample them to be sure they are real, you are more than welcome to send them my way. LOL Enjoy your smokes! I've had a couple of the Diplo #4's and have throughly enjoyed them.