diff --git a/application/models/person/Person_model.php b/application/models/person/Person_model.php
index 233cfc751..d955f6401 100644
--- a/application/models/person/Person_model.php
+++ b/application/models/person/Person_model.php
@@ -316,60 +316,72 @@ class Person_model extends DB_Model
 
 	public function checkDuplicate($person_id)
 	{
-		$qry = "
-			WITH person AS (
-				SELECT *
-				FROM public.tbl_person
-				WHERE person_id = ?
-			),
-			allePersonen AS (
-				SELECT p.person_id
-				FROM public.tbl_person p
-					JOIN person
-						ON lower(p.vorname) = lower(person.vorname)
-						AND lower(p.nachname) = lower(person.nachname)
-						AND p.gebdatum = person.gebdatum
-			),
-			lastStatus AS (
-				SELECT DISTINCT ON (tbl_prestudentstatus.prestudent_id)
-					tbl_prestudentstatus.prestudent_id,
-					tbl_prestudentstatus.status_kurzbz,
-					tbl_prestudent.studiengang_kz,
-					tbl_prestudent.person_id
-				FROM public.tbl_prestudentstatus
-				JOIN public.tbl_prestudent USING (prestudent_id)
-				WHERE tbl_prestudent.person_id IN (SELECT person_id FROM allePersonen)
-				ORDER BY tbl_prestudentstatus.prestudent_id, tbl_prestudentstatus.datum DESC, tbl_prestudentstatus.insertamum DESC
-			),
-			interessenten AS (
-				SELECT *
-				FROM lastStatus
+		$qry = "SELECT person_id
+				FROM public.tbl_prestudent p
+				JOIN
+				(
+					SELECT DISTINCT ON(prestudent_id) *
+					FROM public.tbl_prestudentstatus
+					WHERE prestudent_id IN
+						(
+							SELECT prestudent_id
+							FROM public.tbl_prestudent
+							WHERE person_id IN
+							(
+								SELECT p2.person_id
+								FROM public.tbl_person p
+								JOIN public.tbl_person p2
+								ON lower(p.vorname) = lower(p2.vorname)
+								AND lower(p.nachname) = lower(p2.nachname)
+								AND p.gebdatum = p2.gebdatum
+								AND p.person_id = ?
+							)
+						)
+					ORDER BY prestudent_id, datum DESC, insertamum DESC
+				) ps USING(prestudent_id)
+				JOIN public.tbl_status USING(status_kurzbz)
 				WHERE status_kurzbz = 'Interessent'
-			),
-			keineInteressenten AS (
-				SELECT *
-				FROM lastStatus
-				WHERE status_kurzbz != 'Interessent'
-			),
-			doppeltePerson AS (
+				AND studiengang_kz IN
+				(
+					SELECT studiengang_kz
+					FROM public.tbl_prestudent p
+					JOIN
+					(
+						SELECT DISTINCT ON(prestudent_id) *
+						FROM public.tbl_prestudentstatus
+						WHERE prestudent_id IN
+						(
+							SELECT prestudent_id
+							FROM public.tbl_prestudent
+							WHERE person_id IN
+							(
+								SELECT p2.person_id
+								FROM public.tbl_person p
+								JOIN public.tbl_person p2
+								ON lower(p.vorname) = lower(p2.vorname)
+								AND lower(p.nachname) = lower(p2.nachname)
+								AND p.gebdatum = p2.gebdatum
+								AND p.person_id = ?
+							)
+						)
+						ORDER BY prestudent_id, datum DESC, insertamum DESC
+					) ps USING(prestudent_id)
+					JOIN public.tbl_status USING(status_kurzbz)
+					WHERE status_kurzbz = 'Abbrecher'
+				)
+
+				UNION
+
 				SELECT p2.person_id
-				FROM public.tbl_person p1
-				JOIN public.tbl_prestudent ps1 ON ps1.person_id = p1.person_id
-				JOIN public.tbl_person p2
-						ON  lower(p1.vorname) = lower(p2.vorname)
-						AND lower(p1.nachname) = lower(p2.nachname)
-						AND p1.gebdatum = p2.gebdatum
-				WHERE p1.person_id = ?
-				  AND p1.person_id <> p2.person_id
-			)
-			SELECT DISTINCT(interessenten.person_id)
-			FROM interessenten
-				JOIN keineInteressenten
-					ON interessenten.studiengang_kz = keineInteressenten.studiengang_kz
-			WHERE interessenten.person_id = ?
-			UNION
-			SELECT DISTINCT person_id
-			FROM doppeltePerson";
+				FROM tbl_person p1
+				JOIN tbl_prestudent ps ON p1.person_id = ps.person_id
+				INNER JOIN (
+					SELECT vorname, nachname, gebdatum, person.person_id
+					FROM tbl_person person
+					JOIN tbl_prestudent sps ON person.person_id = sps.person_id
+				) p2
+					ON (lower(p1.vorname) = lower(p2.vorname) AND lower(p1.nachname) = lower(p2.nachname) AND p1.gebdatum = p2.gebdatum)
+				WHERE p1.person_id != p2.person_id AND (p1.person_id = ?)";
 
 		return $this->execQuery($qry, array($person_id, $person_id, $person_id));
 	}