Why OnTriggerEnter2d multiple times if the object has an animator?

If a player has a collision with the static image, then a collision happens 1 time. But if the image is animated, the repeated collision, even if the player does not move.

void OnTriggerEnter2D(Collider2D other) {
  if(other.gameObject.tag == "nanim") {
    //Happens once
    print(other.gameObject.tag);
  }
  if(other.gameObject.tag == "anim") {
    //Happens many times
    print(other.gameObject.tag);
  }
}

good question…it’s a stupid unity bug, i’m getting crazy…