This happened recently to me, opposing character ( A ) had ,energy explosion and damage value 3, he targeted with a ranged attack and hit two of my characters who were adjacent with each other he divided the damage value in 1(character B) and 2 (character C), now my question, he told me each one suffered 2 extra damage because of the Energy Explosion so character B suffered 3 dmg. and character C suffered 4 dmg, he used Energy Explosion correctly?

No. The Area of Effect only includes untargeted characters adjacent to hit targets (see underlined). Hit targets are dealt normally and all other hit characters are dealt damage based on the number of printed the attacker has (See bolded).

Thanks a lot bro !