diff --git a/src/diffusers/pipelines/controlnet/pipeline_controlnet_union_inpaint_sd_xl.py b/src/diffusers/pipelines/controlnet/pipeline_controlnet_union_inpaint_sd_xl.py
index d5ecfa8a3218..1ee63e5f7db6 100644
--- a/src/diffusers/pipelines/controlnet/pipeline_controlnet_union_inpaint_sd_xl.py
+++ b/src/diffusers/pipelines/controlnet/pipeline_controlnet_union_inpaint_sd_xl.py
@@ -1350,6 +1350,8 @@ def __call__(
 
         if not isinstance(control_image, list):
             control_image = [control_image]
+        else:
+            control_image = control_image.copy()
 
         if not isinstance(control_mode, list):
             control_mode = [control_mode]
diff --git a/src/diffusers/pipelines/controlnet/pipeline_controlnet_union_sd_xl.py b/src/diffusers/pipelines/controlnet/pipeline_controlnet_union_sd_xl.py
index d8c5e5027697..27e627e5bac9 100644
--- a/src/diffusers/pipelines/controlnet/pipeline_controlnet_union_sd_xl.py
+++ b/src/diffusers/pipelines/controlnet/pipeline_controlnet_union_sd_xl.py
@@ -1140,6 +1140,8 @@ def __call__(
 
         if not isinstance(control_image, list):
             control_image = [control_image]
+        else:
+            control_image = control_image.copy()
 
         if not isinstance(control_mode, list):
             control_mode = [control_mode]
diff --git a/src/diffusers/pipelines/controlnet/pipeline_controlnet_union_sd_xl_img2img.py b/src/diffusers/pipelines/controlnet/pipeline_controlnet_union_sd_xl_img2img.py
index 6a535afb1c9c..8547675426e3 100644
--- a/src/diffusers/pipelines/controlnet/pipeline_controlnet_union_sd_xl_img2img.py
+++ b/src/diffusers/pipelines/controlnet/pipeline_controlnet_union_sd_xl_img2img.py
@@ -1286,6 +1286,8 @@ def __call__(
 
         if not isinstance(control_image, list):
             control_image = [control_image]
+        else:
+            control_image = control_image.copy()
 
         if not isinstance(control_mode, list):
             control_mode = [control_mode]