diff --git a/app/DD-Record-Organizer/ModuleHelperMethods.vb b/app/DD-Record-Organizer/ModuleHelperMethods.vb
index 9a4cf05..18b4cb3 100644
--- a/app/DD-Record-Organizer/ModuleHelperMethods.vb
+++ b/app/DD-Record-Organizer/ModuleHelperMethods.vb
@@ -266,7 +266,12 @@ Module ModuleHelperMethods
 
     Public Sub OpenFormConstructor(id As Integer, Optional recordId As Integer = -1)
         Try
+            If CURRENT_OPEN_CONSTRUCTOR_FORMS.Contains(id) Then
+                Exit Sub
+            End If
+
             CURRENT_CONSTRUCTOR_ID = id
+            CURRENT_OPEN_CONSTRUCTOR_FORMS.Add(id)
             Dim frm As New frmConstructor_Main()
             ' frm = frmForm_Constructor.Instance()
 
diff --git a/app/DD-Record-Organizer/ModuleRuntimeVariables.vb b/app/DD-Record-Organizer/ModuleRuntimeVariables.vb
index eff92c6..46937b4 100644
--- a/app/DD-Record-Organizer/ModuleRuntimeVariables.vb
+++ b/app/DD-Record-Organizer/ModuleRuntimeVariables.vb
@@ -47,7 +47,7 @@
     Public CURRENT_DOKARTID As Integer
     Public CURRENT_DOKARTSTRING As String
 
-
+    Public CURRENT_OPEN_CONSTRUCTOR_FORMS As New List(Of Integer)
     Public CURRENT_CONSTRUCTOR_ID As Integer = 1
     Public CURRENT_CONSTRUCTOR_DETAIL_ID As Integer
     Public CURRENT_FILEID As Integer
diff --git a/app/DD-Record-Organizer/frmConstructor_Main.vb b/app/DD-Record-Organizer/frmConstructor_Main.vb
index 57c7650..b2e10e7 100644
--- a/app/DD-Record-Organizer/frmConstructor_Main.vb
+++ b/app/DD-Record-Organizer/frmConstructor_Main.vb
@@ -230,6 +230,8 @@ Public Class frmConstructor_Main
         End If
         ClassWindowLocation.SaveFormLocationSize(Me, CONSTRUCTORID, CURRENT_SCREEN_ID, "CONSTRUCTOR_MAIN")
 
+        CURRENT_OPEN_CONSTRUCTOR_FORMS.Remove(CONSTRUCTORID)
+
         ' Verhindert, das noch geöffnete Records für immer gelockt sind
         If Not IsNothing(CURRENT_DOCVIEW) Then
             Try