Will a copy of Volo's triggered ability create another copy of the creature spell?

Question

If I copy Volo, Guide to Monsters triggered ability with Strionic Resonator after casting a unique creature, does the original triggered ability check "doesn’t share a creature type with a creature you control or a creature card in your graveyard" again on resolution? Will I have 3 creatures or 2?

Answer 1

You will have 3 creatures.

The trigger condition is not checked again upon resolution; the "Whenever you cast a creature spell that doesn’t share a creature type with a creature you control or a creature card in your graveyard" is only the condition that causes it to trigger in the first place.

Certain trigger conditions are checked again upon resolution, but they have a specific wording:

603.4. A triggered ability may read “When/Whenever/At [trigger event], if [condition], [effect].” When the trigger event occurs, the ability checks whether the stated condition is true. The ability triggers only if it is; otherwise it does nothing. If the ability triggers, it checks the stated condition again as it resolves. If the condition isn’t true at that time, the ability is removed from the stack and does nothing. Note that this mirrors the check for legal targets. This rule is referred to as the “intervening ‘if’ clause” rule.

So if Volo, Guide to Monsters instead were worded such as "Whenever you cast a creature spell, if that spell doesn’t share a creature type with a creature you control or a creature card in your graveyard..." then in that case, the copy of the trigger would be checked again upon resolution and do nothing.

Answer 2

The clause "that doesn’t share a creature type with a creature you control or a creature card in your graveyard" is part of the trigger condition. It is only checked as the ability triggers, not as it resolves. So, the copy of the ability resolves just fine and you will get 2 copies of the creature, for a total of 3 creatures.

So called "intervening 'if' clauses" are the ones that are checked both as the ability triggers and as it resolves. Those clauses are described in rule 603.4. A similar ability with an "intervening 'if' clause" would be worded like this:

Whenever you cast a creature spell, if it doesn’t share a creature type with a creature you control or a creature card in your graveyard, copy that spell.

Answer 3

You will get 3 creatures.

Technically, with Volo out, you could respond to the cast triggers with a flash creature of the same type and still get the copies of both creatures, since no creature is actually on the battlefield yet. All of the casting and copies are on the stack.