diff --git a/backend-compliance/migrations/158_dedup_doc_check_controls.sql b/backend-compliance/migrations/158_dedup_doc_check_controls.sql
new file mode 100644
index 00000000..52b98be1
--- /dev/null
+++ b/backend-compliance/migrations/158_dedup_doc_check_controls.sql
@@ -0,0 +1,27 @@
+-- 158_dedup_doc_check_controls.sql
+-- Behebt die historische Triplikation von compliance.doc_check_controls
+-- (Dump-Artefakt: kein PK/Unique -> identische Zeilen mehrfach; prod 3x).
+-- Idempotent + verhindert Wiederkehr. macmini ist bereits dedupt (no-op),
+-- prod wird 1713->571 / 1143->381 / 225->75 dedupt.
+-- [migration-approved]
+
+-- 1) Dedup: pro (doc_type, control_id) nur die Zeile mit kleinster ctid behalten.
+DELETE FROM compliance.doc_check_controls a
+USING compliance.doc_check_controls b
+WHERE a.ctid > b.ctid
+  AND a.doc_type   IS NOT DISTINCT FROM b.doc_type
+  AND a.control_id IS NOT DISTINCT FROM b.control_id;
+
+-- 2) Wiederkehr verhindern: Unique-Constraint auf (doc_type, control_id).
+DO $do$
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM pg_constraint
+    WHERE conname = 'uq_doc_check_controls_doctype_control'
+  ) THEN
+    ALTER TABLE compliance.doc_check_controls
+      ADD CONSTRAINT uq_doc_check_controls_doctype_control
+      UNIQUE (doc_type, control_id);
+  END IF;
+END
+$do$;