diff --git a/src/revpimodio2/__about__.py b/src/revpimodio2/__about__.py
index e83737c..78874e4 100644
--- a/src/revpimodio2/__about__.py
+++ b/src/revpimodio2/__about__.py
@@ -3,4 +3,4 @@
 __author__ = "Sven Sager <akira@revpimodio.org>"
 __copyright__ = "Copyright (C) 2023 Sven Sager"
 __license__ = "LGPLv2"
-__version__ = "2.6.0"
+__version__ = "2.6.1rc1"
diff --git a/src/revpimodio2/device.py b/src/revpimodio2/device.py
index 0f27359..6631e59 100644
--- a/src/revpimodio2/device.py
+++ b/src/revpimodio2/device.py
@@ -155,7 +155,7 @@ class Device(object):
         self.__my_io_list = []
         self._selfupdate = False
         self._shared_procimg = False
-        self._shared_write = []
+        self._shared_write = set()
         self.shared_procimg(parentmodio._shared_procimg)  # Set with register
 
         # Wertzuweisung aus dict_device
diff --git a/src/revpimodio2/io.py b/src/revpimodio2/io.py
index 7e1fdfc..df72dc5 100644
--- a/src/revpimodio2/io.py
+++ b/src/revpimodio2/io.py
@@ -706,10 +706,9 @@ class IOBase(object):
             # Für Bitoperationen sperren
             self._parentdevice._filelock.acquire()
 
-            if self._parentdevice._shared_procimg \
-                    and self not in self._parentdevice._shared_write:
+            if self._parentdevice._shared_procimg:
                 # Mark this IO for write operations
-                self._parentdevice._shared_write.append(self)
+                self._parentdevice._shared_write.add(self)
 
             # Hier gibt es immer nur ein byte, als int holen
             int_byte = self._parentdevice._ba_devdata[self._slc_address.start]
@@ -743,11 +742,10 @@ class IOBase(object):
                     )
                 )
 
-            if self._parentdevice._shared_procimg \
-                    and self not in self._parentdevice._shared_write:
+            if self._parentdevice._shared_procimg:
                 with self._parentdevice._filelock:
                     # Mark this IO as changed
-                    self._parentdevice._shared_write.append(self)
+                    self._parentdevice._shared_write.add(self)
 
             self._parentdevice._ba_devdata[self._slc_address] = value