diff --git a/htdocs/comm/action/class/actioncomm.class.php b/htdocs/comm/action/class/actioncomm.class.php
index a1c0ee2badf..1e506526a1d 100644
--- a/htdocs/comm/action/class/actioncomm.class.php
+++ b/htdocs/comm/action/class/actioncomm.class.php
@@ -579,20 +579,25 @@ class ActionComm extends CommonObject
 			// Now insert assigned users
 			if (!$error) {
 				//dol_syslog(var_export($this->userassigned, true));
+				$already_inserted = array();
 				foreach ($this->userassigned as $key => $val) {
 					if (!is_array($val)) {	// For backward compatibility when val=id
 						$val = array('id'=>$val);
 					}
 
 					if ($val['id'] > 0) {
+						if (!empty($already_inserted[$val['id']])) continue;
+
 						$sql = "INSERT INTO ".MAIN_DB_PREFIX."actioncomm_resources(fk_actioncomm, element_type, fk_element, mandatory, transparency, answer_status)";
 						$sql .= " VALUES(".$this->id.", 'user', ".$val['id'].", ".(empty($val['mandatory']) ? '0' : $val['mandatory']).", ".(empty($val['transparency']) ? '0' : $val['transparency']).", ".(empty($val['answer_status']) ? '0' : $val['answer_status']).")";
 
 						$resql = $this->db->query($sql);
 						if (!$resql) {
 							$error++;
-							dol_syslog('Error to process userassigned: '.$this->db->lasterror(), LOG_ERR);
+							dol_syslog('Error to process userassigned: ' . $this->db->lasterror(), LOG_ERR);
 							$this->errors[] = $this->db->lasterror();
+						} else {
+							$already_inserted[$val['id']] = true;
 						}
 						//var_dump($sql);exit;
 					}
@@ -601,15 +606,20 @@ class ActionComm extends CommonObject
 
 			if (!$error) {
 				if (!empty($this->socpeopleassigned)) {
+					$already_inserted = array();
 					foreach ($this->socpeopleassigned as $id => $val) {
+						if (!empty($already_inserted[$val['id']])) continue;
+
 						$sql = "INSERT INTO ".MAIN_DB_PREFIX."actioncomm_resources(fk_actioncomm, element_type, fk_element, mandatory, transparency, answer_status)";
 						$sql .= " VALUES(".$this->id.", 'socpeople', ".$id.", 0, 0, 0)";
 
 						$resql = $this->db->query($sql);
 						if (!$resql) {
 							$error++;
-							dol_syslog('Error to process socpeopleassigned: '.$this->db->lasterror(), LOG_ERR);
+							dol_syslog('Error to process socpeopleassigned: ' . $this->db->lasterror(), LOG_ERR);
 							$this->errors[] = $this->db->lasterror();
+						} else {
+							$already_inserted[$val['id']] = true;
 						}
 					}
 				}
@@ -1143,10 +1153,13 @@ class ActionComm extends CommonObject
 				$sql = "DELETE FROM ".MAIN_DB_PREFIX."actioncomm_resources where fk_actioncomm = ".$this->id." AND element_type = 'user'";
 				$resql = $this->db->query($sql);
 
+				$already_inserted = array();
 				foreach ($this->userassigned as $key => $val) {
 					if (!is_array($val)) {	// For backward compatibility when val=id
 						$val = array('id'=>$val);
 					}
+					if (!empty($already_inserted[$val['id']])) continue;
+
 					$sql = "INSERT INTO ".MAIN_DB_PREFIX."actioncomm_resources(fk_actioncomm, element_type, fk_element, mandatory, transparency, answer_status)";
 					$sql .= " VALUES(".$this->id.", 'user', ".$val['id'].", ".(empty($val['mandatory']) ? '0' : $val['mandatory']).", ".(empty($val['transparency']) ? '0' : $val['transparency']).", ".(empty($val['answer_status']) ? '0' : $val['answer_status']).")";
 
@@ -1154,6 +1167,8 @@ class ActionComm extends CommonObject
 					if (!$resql) {
 						$error++;
 						$this->errors[] = $this->db->lasterror();
+					} else {
+						$already_inserted[$val['id']] = true;
 					}
 					//var_dump($sql);exit;
 				}
@@ -1164,7 +1179,10 @@ class ActionComm extends CommonObject
 				$resql = $this->db->query($sql);
 
 				if (!empty($this->socpeopleassigned)) {
+					$already_inserted = array();
 					foreach (array_keys($this->socpeopleassigned) as $id) {
+						if (!empty($already_inserted[$val['id']])) continue;
+
 						$sql = "INSERT INTO ".MAIN_DB_PREFIX."actioncomm_resources(fk_actioncomm, element_type, fk_element, mandatory, transparency, answer_status)";
 						$sql .= " VALUES(".$this->id.", 'socpeople', ".$id.", 0, 0, 0)";
 
@@ -1172,6 +1190,8 @@ class ActionComm extends CommonObject
 						if (!$resql) {
 							$error++;
 							$this->errors[] = $this->db->lasterror();
+						} else {
+							$already_inserted[$val['id']] = true;
 						}
 					}
 				}