server/AyaNova/DataList/DataListSqlSelectBuilder.cs

@@ -87,16 +87,24 @@ namespace AyaNova.DataList
                     }
                     else
                     {
-                        sb.Append(", ");
-                        sb.Append(o.GetSqlValueColumnName());
-                        map.Add(o.GetSqlValueColumnName(), ++nOrdinal);
-
-                        //does it also have an ID column?
-                        if (!string.IsNullOrWhiteSpace(o.SqlIdColumnName))
+                        var valueColumnName = o.GetSqlValueColumnName();
+                        if (!map.ContainsKey(valueColumnName))
                         {
                             sb.Append(", ");
-                            sb.Append(o.SqlIdColumnName);
-                            map.Add(o.SqlIdColumnName, ++nOrdinal);
+                            sb.Append(valueColumnName);
+                            map.Add(valueColumnName, ++nOrdinal);
+                        }
+
+                        //does it also have an ID column?
+                        var idColumnName = o.SqlIdColumnName;
+                        if (!string.IsNullOrWhiteSpace(idColumnName))
+                        {
+                            if (!map.ContainsKey(idColumnName))
+                            {
+                                sb.Append(", ");
+                                sb.Append(idColumnName);
+                                map.Add(idColumnName, ++nOrdinal);
+                            }
                         }
                     }