Index: unit_config_reader.php
===================================================================
--- unit_config_reader.php	(revision 13274)
+++ unit_config_reader.php	(working copy)
@@ -825,7 +825,11 @@
 		}
 
 		$this->Application->HandleEvent( new kEvent($prefix . ':OnAfterConfigRead') );
-		array_push($this->AfterConfigProcessed, $prefix);
+
+		if (!(defined('IS_INSTALL') && IS_INSTALL)) {
+			// allow to call OnAfterConfigRead multiple times during install
+			array_push($this->AfterConfigProcessed, $prefix);
+		}
 	}
 
 	/**