Would a Tempest Cleric's Booming Blade, transmuted to lightning damage, knock a target away twice?

Question

Let's assume a chain of events. We have a level six Tempest Cleric, who has access to Booming Blade through some combination of racial spell, feat, or multi-classing.

Further, also through feat or multiclassing, the character has picked up the Transmuted Spell metamagic.

When you cast a spell that deals a type of damage from the following list, you can spend 1 sorcery point to change that damage type to one of the other listed types: acid, cold, fire, lightning, poison, thunder.

Booming Blade deals thunder damage, so it is eligible for this metamagic. Further, although it deals this damage twice, the wording of the metamagic does not limit it to only one roll, so we can assume it lets us replace both instances of damage with, in this case, lightning damage.

However, our character is a level six Tempest Cleric, and has access to the Thunderous Strike feature.

Thunderous Strike. At 6th level, when you deal lightning damage to a Large or smaller creature, you can also push it up to 10 feet away from you.

My question is, is there a reason the following wouldn't work: We hit a creature with our lightning-transmuted Booming Blade, pushing it 10 feet away from us. On its own turn, the creature decides to close the distance - thus triggering the movement clause of Booming Blade, taking additional lightning damage and, because of Thunderous Strike, being pushed away again.

Answer 1

Yes, double push

Transmuted Spell does not change the damage type of a roll, and it doesn't have a specific duration; it changes one damage type for a spell to a different damage type. The most reasonable interpretation to me is that all instances of damage type A are changed to damage type B for the duration of that spell; the wording is a bit imprecise, but I think any other intention would be worded differently. Thus, for a level 6 character Transmuted Booming Blade can deal Lightning damage instead of Thunder, and it will change both the immediate damage and the lingering damage.

The Thunderous Strike feature is more straightforward. Thunderous strike has no timing restrictions, no action requirement, no resource costs, and no "once per turn" or "once per round". Every single time the Tempest Cleric deals Lightning Damage to a Large or smaller creature they have the option to use Thunderous Strike, including multiple times from the same spell, multiple times in the same turn, and even during other characters' turns.