Shattering Spree + Trinisphere

[matelml]

How much does it cost to destroy 3 artifacts with Shattering Spree if there is a Trinisphere in play? It would seem 2RRR, but a judge told me RRR.

[Taurelin]

502.52a Replicate is a keyword that represents two abilities. The first is a static ability that functions while the spell is on the stack. The second is a triggered ability that functions while the spell is on the stack. “Replicate [cost]” means “As an additional cost to play this spell, you may pay [cost] any number of times” and “When you play this spell, if a replicate cost was paid for it, copy it for each time its replicate cost was paid. If the spell has any targets, you may choose new targets for any number of the copies.” Paying a spell’s replicate cost follows the rules for paying additional costs in rules 409.1b and 409.1f–h.

That means if you replicate the spell twice to destroy three artifacts, you already invest 3 mana for the spell, so Trinisphere won't have an effect anymore.

[matelml]

Thanks!