diff --git a/htdocs/core/class/commonobject.class.php b/htdocs/core/class/commonobject.class.php
index 85987c8a3cf..1064d34561d 100644
--- a/htdocs/core/class/commonobject.class.php
+++ b/htdocs/core/class/commonobject.class.php
@@ -5843,8 +5843,15 @@ abstract class CommonObject
 				$attributeLabel    = $extrafields->attributes[$this->table_element]['label'][$attributeKey];
 				$attributeParam    = $extrafields->attributes[$this->table_element]['param'][$attributeKey];
 				$attributeRequired = $extrafields->attributes[$this->table_element]['required'][$attributeKey];
+				$attributeUnique   = $extrafields->attributes[$this->table_element]['unique'][$attributeKey];
 				$attrfieldcomputed = $extrafields->attributes[$this->table_element]['computed'][$attributeKey];
 
+				// If we clone, we have to clean unique extrafields to prevent duplicates.
+				// This behaviour can be prevented by external code by changing $this->context['createfromclone'] value in createFrom hook
+				if (! empty($this->context['createfromclone']) && $this->context['createfromclone'] == 'createfromclone' && ! empty($attributeUnique)) {
+					$new_array_options[$key] = null;
+				}
+
 				// Similar code than into insertExtraFields
 				if ($attributeRequired) {
 					$mandatorypb = false;