diff --git a/api/index.php b/api/index.php
index 770f3d1..d651c39 100644
--- a/api/index.php
+++ b/api/index.php
@@ -9059,11 +9059,14 @@ function importMergeBackup(PDO $db): void {
             $stats['products']++;
         }
 
-        // --- 3. inventory : toujours inséré, product_id remappé ---
+// --- 3. inventory : skip si même (product_id, location, expiry_date, quantity) existe déjà ---
         $rows = $src->query("SELECT * FROM inventory")->fetchAll();
         foreach ($rows as $row) {
             $newPid = $productMap[(int)$row['product_id']] ?? null;
             if (!$newPid) continue;
+            $exists = $db->prepare("SELECT 1 FROM inventory WHERE product_id = ? AND location = ? AND COALESCE(expiry_date,'') = COALESCE(?,'') AND ABS(quantity - ?) < 0.001");
+            $exists->execute([$newPid, $row['location'], $row['expiry_date'] ?? null, $row['quantity']]);
+            if ($exists->fetch()) continue;
             unset($row['id']);
             $row['product_id'] = $newPid;
             $cols = array_keys($row);
@@ -9072,11 +9075,14 @@ function importMergeBackup(PDO $db): void {
             $stats['inventory']++;
         }
 
-        // --- 4. transactions : toujours insérées, product_id remappé ---
+        // --- 4. transactions : skip si même (product_id, type, quantity, created_at) existe déjà ---
         $rows = $src->query("SELECT * FROM transactions")->fetchAll();
         foreach ($rows as $row) {
             $newPid = $productMap[(int)$row['product_id']] ?? null;
             if (!$newPid) continue;
+            $exists = $db->prepare("SELECT 1 FROM transactions WHERE product_id = ? AND type = ? AND ABS(quantity - ?) < 0.001 AND created_at = ?");
+            $exists->execute([$newPid, $row['type'], $row['quantity'], $row['created_at']]);
+            if ($exists->fetch()) continue;
             unset($row['id']);
             $row['product_id'] = $newPid;
             $cols = array_keys($row);
@@ -9111,9 +9117,12 @@ function importMergeBackup(PDO $db): void {
             $stats['recipe_library']++;
         }
 
-        // --- 7. chat_messages : toujours insérés ---
+        // --- 7. chat_messages : skip si même (role, text, created_at) existe déjà ---
         $rows = $src->query("SELECT * FROM chat_messages")->fetchAll();
         foreach ($rows as $row) {
+            $exists = $db->prepare("SELECT 1 FROM chat_messages WHERE role = ? AND text = ? AND created_at = ?");
+            $exists->execute([$row['role'], $row['text'], $row['created_at']]);
+            if ($exists->fetch()) continue;
             unset($row['id']);
             $cols = array_keys($row);
             $stmt = $db->prepare("INSERT INTO chat_messages (" . implode(',', $cols) . ") VALUES (" . implode(',', array_fill(0, count($cols), '?')) . ")");