Card: Overseer of the Damned - Problem: trigger twice

[VHBT]

Hello, thank you for made this magnific way to build and test decks.

Well, I'm here cause of "Overseer of the Damned".This card's effect triggers twice to create zombie tokens. Every time I tested the effect it happened twice, generating twice as many tokens as it should have. Sorry for my bad english, I'm Brazilian ;P

[VHBT]

Sorry, I forgot to say, this happens when he enters through the effect of the Battle Invasion of Amonkhet.