diff --git a/app/features/sendouq-match/SQMatchRepository.server.test.ts b/app/features/sendouq-match/SQMatchRepository.server.test.ts
index 4018de171..5b36bdfab 100644
--- a/app/features/sendouq-match/SQMatchRepository.server.test.ts
+++ b/app/features/sendouq-match/SQMatchRepository.server.test.ts
@@ -460,6 +460,58 @@ describe("finalizeMatch", () => {
 			playerResults.map(() => matchSeason.nth),
 		);
 	});
+
+	// Demonstrates a bug: reportMapWinner checks the match lock on a snapshot read
+	// outside the finalizing transaction, so two teammates confirming the score at
+	// the same time both finalize. Rating/stat changes get applied twice.
+	test("concurrent score confirmations finalize the match only once", async () => {
+		const setup = await setupMatch();
+
+		let reportedCount = 0;
+		let result = await SQMatchRepository.reportMapWinner({
+			matchId: setup.match.id,
+			winnerId: setup.alphaGroupId,
+			reportedByUserId: setup.alphaMembers[0].id,
+			reportedCount,
+		});
+		while (result.status === "MAP_REPORTED") {
+			reportedCount++;
+			result = await SQMatchRepository.reportMapWinner({
+				matchId: setup.match.id,
+				winnerId: setup.alphaGroupId,
+				reportedByUserId: setup.alphaMembers[0].id,
+				reportedCount,
+			});
+		}
+		expect(result.status).toBe("MATCH_REPORTED");
+
+		const skillsBeforeConfirm = await fetchSkills(setup.match.id);
+
+		const [first, second] = await Promise.all([
+			SQMatchRepository.reportMapWinner({
+				matchId: setup.match.id,
+				winnerId: setup.alphaGroupId,
+				reportedByUserId: setup.bravoMembers[0].id,
+				reportedCount: reportedCount + 1,
+			}),
+			SQMatchRepository.reportMapWinner({
+				matchId: setup.match.id,
+				winnerId: setup.alphaGroupId,
+				reportedByUserId: setup.bravoMembers[1].id,
+				reportedCount: reportedCount + 1,
+			}),
+		]);
+
+		const finalizedCount = [first, second].filter(
+			(r) => r.status === "MATCH_FINALIZED",
+		).length;
+		expect(finalizedCount).toBe(1);
+
+		const skillsAfterConfirm = await fetchSkills(setup.match.id);
+		const skillsFromThisFinalization =
+			skillsAfterConfirm.length - skillsBeforeConfirm.length;
+		expect(skillsFromThisFinalization).toBe(FULL_GROUP_SIZE * 2 + 2);
+	});
 });
 
 describe("undoMatchReport", () => {
diff --git a/app/features/sendouq-match/SQMatchRepository.server.ts b/app/features/sendouq-match/SQMatchRepository.server.ts
index 372dcbdb2..ae6b3b2b7 100644
--- a/app/features/sendouq-match/SQMatchRepository.server.ts
+++ b/app/features/sendouq-match/SQMatchRepository.server.ts
@@ -1179,7 +1179,7 @@ async function handleMatchConfirmation({
 		.filter((m) => m.winnerGroupId !== null)
 		.map((m) => (m.winnerGroupId === match.groupAlpha.id ? "ALPHA" : "BRAVO"));
 
-	await finalizeMatch({
+	const finalized = await finalizeMatch({
 		match,
 		members,
 		winners,
@@ -1190,6 +1190,10 @@ async function handleMatchConfirmation({
 			SQGroupRepository.setAsInactive(groupToDeactivate, trx),
 	});
 
+	if (!finalized) {
+		return { status: "ALREADY_LOCKED" };
+	}
+
 	return { status: "MATCH_FINALIZED" };
 }
 
@@ -1225,7 +1229,7 @@ async function handleStaffFinalization({
 		winnerId === match.groupAlpha.id ? "ALPHA" : "BRAVO",
 	];
 
-	await finalizeMatch({
+	const finalized = await finalizeMatch({
 		match,
 		members,
 		winners,
@@ -1247,6 +1251,10 @@ async function handleStaffFinalization({
 		},
 	});
 
+	if (!finalized) {
+		return { status: "ALREADY_LOCKED" };
+	}
+
 	return { status: "MATCH_FINALIZED" };
 }
 
@@ -1289,7 +1297,10 @@ async function finalizeMatch({
 		loserGroupId,
 	});
 
-	await db.transaction().execute(async (trx) => {
+	return db.transaction().execute(async (trx) => {
+		const { isLocked, confirmedAt } = await findLockState(match.id, trx);
+		if (isLocked || confirmedAt) return false;
+
 		if (preFinalize) await preFinalize(trx);
 		await trx
 			.updateTable("GroupMatch")
@@ -1322,9 +1333,27 @@ async function finalizeMatch({
 			},
 			trx,
 		);
+
+		return true;
 	});
 }
 
+/** Lock state read inside the finalizing transaction so concurrent confirmations can't both finalize. */
+function findLockState(matchId: number, trx: Transaction<DB>) {
+	return trx
+		.selectFrom("GroupMatch")
+		.select(({ exists, selectFrom }) => [
+			"GroupMatch.confirmedAt",
+			exists(
+				selectFrom("Skill")
+					.select("Skill.id")
+					.where("Skill.groupMatchId", "=", matchId),
+			).as("isLocked"),
+		])
+		.where("GroupMatch.id", "=", matchId)
+		.executeTakeFirstOrThrow();
+}
+
 /** Matches created before the given cutoff whose score was never confirmed and that no cancellation has locked. */
 export function findUnfinishedMatchesCreatedBefore(cutoff: Date) {
 	return db
@@ -1394,7 +1423,7 @@ export async function resolveUnfinishedMatch(
 		.filter((m) => m.winnerGroupId !== null)
 		.map((m) => (m.winnerGroupId === match.groupAlpha.id ? "ALPHA" : "BRAVO"));
 
-	await finalizeMatch({
+	const finalized = await finalizeMatch({
 		match,
 		members: buildMembers(match),
 		winners,
@@ -1407,6 +1436,10 @@ export async function resolveUnfinishedMatch(
 		},
 	});
 
+	if (!finalized) {
+		return { status: "ALREADY_LOCKED" };
+	}
+
 	return { status: "CONFIRMED" };
 }