diff U3 a/includes/RadioactivityFileIncidentStorage.inc b/includes/RadioactivityFileIncidentStorage.inc
--- a/includes/RadioactivityFileIncidentStorage.inc	Thu Mar 06 06:59:59 2014
+++ b/includes/RadioactivityFileIncidentStorage.inc	Tue Nov 04 15:11:22 2014
@@ -22,7 +22,8 @@
   public function addIncident(RadioactivityIncident $incident) {
     $row  = serialize($incident);
     $tmp  = VAR_RADIOACTIVITY_TEMP_DIR;
-    $file = $tmp . "/radioactivity-payload.txt";
+    $site = preg_replace('#[^-\.0-9a-z]+#iu', '_', $_SERVER['SERVER_NAME']);
+    $file = "$tmp/radioactivity-$site.txt";
     $fh   = fopen($file, "a+");
     fwrite($fh, $row . PHP_EOL);
     fclose($fh);
@@ -41,9 +42,8 @@
     self::$cronDone = TRUE;
 
     $tmp = VAR_RADIOACTIVITY_TEMP_DIR;
-
-    $file = $tmp . "/radioactivity-payload.txt";
-
+    $site = preg_replace('#[^-\.0-9a-z]+#iu', '_', $_SERVER['SERVER_NAME']);
+    $file = "$tmp/radioactivity-$site.txt";
     if (file_exists($file)) {
       // get file contents and clear file
       $fh = fopen($file, "r");