diff --git a/quality.py b/quality.py
index dda50ca..ae3bb02 100644
--- a/quality.py
+++ b/quality.py
@@ -92,6 +92,7 @@ class QualitySample(ModelSQL, ModelView):
         pool = Pool()
         Config = pool.get('quality.configuration')
 
+        vlist = [x.copy() for x in vlist]
         sequence = Config(1).sample_sequence
         for value in vlist:
             if not value.get('code'):