Does the Manticore - Greater Beast ability "While active, deal 1 damage to each opposing character immediatley after it is fielded" stack?

Played a game where my opponent had three Manticore - Greater Beast dice active and we were dealing three damage to my fielded dice.

In re-reading the rules they state

"• Active and Fielded
When game text says, “While ___ is active,” that means “When one
or more of this card’s dice are in the field.” In other words, when dice
of that character have been fielded, the effect on the card takes place.
It takes place only once, no matter how many copies of that die are
fielded."

Leads me to think we should have been dealing only 1 damage to my fielded characters.

Thanks

1 damage - while active is satisfied by having 1 or more dice fielded

Good deal. Thanks.