diff --git a/includes/class-tmdo-installer.php b/includes/class-tmdo-installer.php
index da1244a..4485e4c 100644
--- a/includes/class-tmdo-installer.php
+++ b/includes/class-tmdo-installer.php
@@ -217,6 +217,15 @@ class TMDO_Installer {
 		// Idempotent — only creates tables that don't already exist.
 		self::install_v2_tables();
 
+		// 1.4.2: archive sweeps before this release copied trashed meta daily.
+		if ( class_exists( 'TMDO_Zone_Archive' ) ) {
+			global $wpdb;
+			$archive = TMDO_Zone_Archive::table();
+			if ( $archive === $wpdb->get_var( $wpdb->prepare( 'SHOW TABLES LIKE %s', $wpdb->esc_like( $archive ) ) ) ) {
+				TMDO_Zone_Archive::remove_duplicates();
+			}
+		}
+
 		update_option( 'wpdo_db_version', self::SCHEMA_VERSION );
 
 		// Register wpdo_features with autoload=no so it doesn't inflate every page load.
@@ -1440,7 +1449,8 @@ class TMDO_Installer {
   original_meta_id bigint(20) unsigned NOT NULL DEFAULT 0,
   PRIMARY KEY (id),
   KEY idx_post_id (post_id),
-  KEY idx_post_type_date (post_type, archived_at)
+  KEY idx_post_type_date (post_type, archived_at),
+  KEY idx_original_meta (original_meta_id)
 ) {$charset};";
 
 		foreach ( $sqls as $sql ) {
diff --git a/includes/zones/class-tmdo-zone-archive.php b/includes/zones/class-tmdo-zone-archive.php
index ccce528..bed8eb3 100644
--- a/includes/zones/class-tmdo-zone-archive.php
+++ b/includes/zones/class-tmdo-zone-archive.php
@@ -210,7 +210,11 @@ class TMDO_Zone_Archive {
 		global $wpdb;
 
 		$cutoff = gmdate( 'Y-m-d H:i:s', time() - ( $days * DAY_IN_SECONDS ) );
+		// Rows already archived are skipped: the sweep used to copy the same
+		// trashed meta again every day (2.4.2 PR-136).
+		$table = self::table();
 
+		// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table name from internal self::table()
 		$rows = $wpdb->get_results(
 			$wpdb->prepare(
 				"SELECT pm.meta_id, pm.post_id, pm.meta_key, pm.meta_value, p.post_type
@@ -218,12 +222,14 @@ class TMDO_Zone_Archive {
 				 INNER JOIN {$wpdb->posts} p ON p.ID = pm.post_id
 				 WHERE p.post_status = 'trash'
 				   AND p.post_modified_gmt < %s
+				   AND NOT EXISTS ( SELECT 1 FROM `{$table}` a WHERE a.original_meta_id = pm.meta_id )
 				 LIMIT %d",
 				$cutoff,
 				$limit
 			),
 			ARRAY_A
 		);
+		// phpcs:enable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
 
 		if ( ! $rows ) {
 			return 0;
@@ -245,6 +251,21 @@ class TMDO_Zone_Archive {
 		return count( $entries );
 	}
 
+	/**
+	 * Delete archive rows that copy the same original meta row again, keeping
+	 * the first copy (sweeps before 1.4.2 archived trashed meta every day).
+	 * Rows without an original meta id are left alone.
+	 *
+	 * @return int Rows deleted.
+	 */
+	public static function remove_duplicates(): int {
+		global $wpdb;
+		$table = self::table();
+		// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table name from internal self::table()
+		$deleted = $wpdb->query( "DELETE FROM `{$table}` WHERE original_meta_id > 0 AND id NOT IN ( SELECT keep_id FROM ( SELECT MIN(id) AS keep_id FROM `{$table}` WHERE original_meta_id > 0 GROUP BY original_meta_id ) AS k )" );
+		return is_int( $deleted ) ? $deleted : 0;
+	}
+
 	/**
 	 * Get archive statistics.
 	 *
diff --git a/tests/integration/ZoneArchiveIntegrationTest.php b/tests/integration/ZoneArchiveIntegrationTest.php
index 1c12e21..462da4b 100644
--- a/tests/integration/ZoneArchiveIntegrationTest.php
+++ b/tests/integration/ZoneArchiveIntegrationTest.php
@@ -45,6 +45,55 @@ class ZoneArchiveIntegrationTest extends TestCase {
 		$GLOBALS['_wp_postmeta'] = [];
 	}
 
+	// ── sweep / duplicates (2.4.2 PR-136, manual F-6) ─────────────────────
+
+	/** Posts and postmeta for sweep(): post 10 trashed 200 days ago, post 11 published. */
+	private function seed_trashed_post(): void {
+		global $wpdb;
+		$wpdb->query( "DROP TABLE IF EXISTS `{$wpdb->posts}`" );
+		$wpdb->query( "DROP TABLE IF EXISTS `{$wpdb->postmeta}`" );
+		$wpdb->query( "CREATE TABLE `{$wpdb->posts}` ( ID BIGINT UNSIGNED NOT NULL, post_type VARCHAR(20) NOT NULL DEFAULT 'post', post_status VARCHAR(20) NOT NULL DEFAULT 'publish', post_modified_gmt DATETIME NOT NULL DEFAULT '2000-01-01 00:00:00', PRIMARY KEY (ID) ) ENGINE=InnoDB" );
+		$wpdb->query( "CREATE TABLE `{$wpdb->postmeta}` ( meta_id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT, post_id BIGINT UNSIGNED NOT NULL DEFAULT 0, meta_key VARCHAR(255) DEFAULT NULL, meta_value LONGTEXT, PRIMARY KEY (meta_id) ) ENGINE=InnoDB" );
+		$old = gmdate( 'Y-m-d H:i:s', time() - 200 * DAY_IN_SECONDS );
+		$wpdb->query( "INSERT INTO `{$wpdb->posts}` VALUES (10, 'hp_listing', 'trash', '{$old}'), (11, 'hp_listing', 'publish', '{$old}')" );
+		$wpdb->query( "INSERT INTO `{$wpdb->postmeta}` (post_id, meta_key, meta_value) VALUES (10, 'hp_price', '5'), (10, 'hp_rating', '4'), (11, 'hp_price', '9')" );
+	}
+
+	private function drop_posts(): void {
+		global $wpdb;
+		$wpdb->query( "DROP TABLE IF EXISTS `{$wpdb->posts}`" );
+		$wpdb->query( "DROP TABLE IF EXISTS `{$wpdb->postmeta}`" );
+	}
+
+	private function archive_rows(): int {
+		global $wpdb;
+		return (int) $wpdb->get_var( 'SELECT COUNT(*) FROM `' . self::TABLE . '`' );
+	}
+
+	public function test_sweep_copies_each_trashed_meta_row_once(): void {
+		$this->seed_trashed_post();
+		try {
+			$this->assertSame( 2, WPDO_Zone_Archive::sweep( 90, false ) );
+			$this->assertSame( 0, WPDO_Zone_Archive::sweep( 90, false ), 'already archived' );
+			$this->assertSame( 2, $this->archive_rows() );
+		} finally {
+			$this->drop_posts();
+		}
+	}
+
+	public function test_remove_duplicates_keeps_the_first_copy_of_each_meta_row(): void {
+		WPDO_Zone_Archive::archive( 10, 'hp_listing', 'hp_price', '5', 101 );
+		WPDO_Zone_Archive::archive( 10, 'hp_listing', 'hp_price', '5', 101 );
+		WPDO_Zone_Archive::archive( 10, 'hp_listing', 'hp_rating', '4', 102 );
+		WPDO_Zone_Archive::archive( 10, 'hp_listing', 'hp_rating', '4', 102 );
+		WPDO_Zone_Archive::archive( 12, 'hp_listing', 'hp_price', '7' ); // original_meta_id 0: no identity, kept.
+		WPDO_Zone_Archive::archive( 12, 'hp_listing', 'hp_price', '7' );
+
+		$this->assertSame( 2, WPDO_Zone_Archive::remove_duplicates() );
+		$this->assertSame( 4, $this->archive_rows() );
+		$this->assertSame( 0, WPDO_Zone_Archive::remove_duplicates() );
+	}
+
 	// ── archive / get ─────────────────────────────────────────────────────
 
 	public function test_archive_stores_plain_entry(): void {