If you EV one Pokemon, your payment is either a copy of what you trained or another Pokemon, not get both... That is the standard.
You may also do this Eevee (4 HP / 252 SpA / 252 Spe and keep as Eevee)
EV Mewtwo for Zapdos
EV Eevee for Ditto
I will trade Mewtwo and Eevee to you, when you're done training, you get Ditto and Zapdos. Pretty good. Use 2278 8850 1101, message back when you are aroundddd.