diff --git a/app/models/modules.py b/app/models/modules.py
index f5a978c2..854a8a8b 100644
--- a/app/models/modules.py
+++ b/app/models/modules.py
@@ -85,14 +85,28 @@ class Module(db.Model):
         Les coefs nuls (zéro) ne sont pas stockés: la relation est supprimée.
         """
         ue_coefs = []
+        changed = False
         for ue_id, coef in ue_coef_dict.items():
-            ue = UniteEns.query.get(ue_id)
-            if coef == 0.0:
-                self.delete_ue_coef(ue)
+            # Existant ?
+            coefs = [c for c in self.ue_coefs if c.ue_id == ue_id]
+            if coefs:
+                ue_coef = coefs[0]
+                if coef == 0.0:  # supprime ce coef
+                    db.session.delete(ue_coef)
+                    changed = True
+                elif coef != ue_coef.coef:
+                    ue_coef.coef = coef
+                    db.session.add(ue_coef)
+                    changed = True
             else:
-                ue_coefs.append(ModuleUECoef(module=self, ue=ue, coef=coef))
-        self.ue_coefs = ue_coefs
-        self.formation.invalidate_module_coefs()
+                # crée nouveau coef:
+                if coef != 0.0:
+                    ue = UniteEns.query.get(ue_id)
+                    ue_coef = ModuleUECoef(module=self, ue=ue, coef=coef)
+                    self.ue_coefs.append(ue_coef)
+                    changed = True
+        if changed:
+            self.formation.invalidate_module_coefs()
 
     def update_ue_coef_dict(self, ue_coef_dict: dict):
         """update coefs vers UE (ajoute aux existants)"""