diff --git a/htdocs/comm/propal/card.php b/htdocs/comm/propal/card.php
index 7b7389b5f7962..3df49b6c20786 100644
--- a/htdocs/comm/propal/card.php
+++ b/htdocs/comm/propal/card.php
@@ -1467,7 +1467,7 @@
 		// warehouse
 		$result = $object->setWarehouse(GETPOST('warehouse_id', 'int'));
 	} elseif ($action == 'update_extras') {
-		$object->oldcopy = dol_clone($object);
+		$object->oldcopy = dol_clone($object, 2);
 
 		// Fill array 'array_options' with data from update form
 		$ret = $extrafields->setOptionalsFromPost(null, $object, GETPOST('attribute', 'restricthtml'));
diff --git a/htdocs/core/lib/functions.lib.php b/htdocs/core/lib/functions.lib.php
index 9827414c3ff96..e9ae5bdfe15ae 100644
--- a/htdocs/core/lib/functions.lib.php
+++ b/htdocs/core/lib/functions.lib.php
@@ -1145,29 +1145,43 @@ function dol_buildpath($path, $type = 0, $returnemptyifnotfound = 0)
 }
 
 /**
- *	Create a clone of instance of object (new instance with same value for properties)
- *  With native = 0: Property that are reference are also new object (full isolation clone). This means $this->db of new object is not valid.
+ *	Create a clone of instance of object (new instance with same value for each properties)
+ *  With native = 0: Property that are reference are different memory area in the new object (full isolation clone). This means $this->db of new object may not be valid.
  *  With native = 1: Use PHP clone. Property that are reference are same pointer. This means $this->db of new object is still valid but point to same this->db than original object.
+ *  With native = 2: Property that are reference are different memory area in the new object (full isolation clone). Only scalar and array values are cloned. This means $this->db of new object is not valid.
  *
  * 	@param	object	$object		Object to clone
- *  @param	int		$native		0=Full isolation method, 1=Native PHP method
+ *  @param	int		$native		0=Full isolation method, 1=Native PHP method, 2=Full isolation method keeping only scalar and array properties (recommended)
  *	@return object				Clone object
  *  @see https://php.net/manual/language.oop5.cloning.php
  */
 function dol_clone($object, $native = 0)
 {
-	if (empty($native)) {
+	if ($native == 0) {
+		// deprecated method, use the method with native = 2 instead
 		$tmpsavdb = null;
 		if (isset($object->db) && isset($object->db->db) && is_object($object->db->db) && get_class($object->db->db) == 'PgSql\Connection') {
 			$tmpsavdb = $object->db;
-			unset($object->db);		// Such property can not be serialized when PgSql/Connection
+			unset($object->db);		// Such property can not be serialized with pgsl (when object->db->db = 'PgSql\Connection')
 		}
 
-		$myclone = unserialize(serialize($object));	// serialize then unserialize is hack to be sure to have a new object for all fields
+		$myclone = unserialize(serialize($object));	// serialize then unserialize is a hack to be sure to have a new object for all fields
 
-		if ($tmpsavdb) {
+		if (!empty($tmpsavdb)) {
 			$object->db = $tmpsavdb;
 		}
+	} elseif ($native == 2) {
+		// recommended method to have a full isolated cloned object
+		$myclone = new stdClass();
+		$tmparray = get_object_vars($object);	// return only public properties
+
+		if (is_array($tmparray)) {
+			foreach ($tmparray as $propertykey => $propertyval) {
+				if (is_scalar($propertyval) || is_array($propertyval)) {
+					$myclone->$propertykey = $propertyval;
+				}
+			}
+		}
 	} else {
 		$myclone = clone $object; // PHP clone is a shallow copy only, not a real clone, so properties of references will keep the reference (refering to the same target/variable)
 	}