diff --git a/gns3server/compute/builtin/nodes/ethernet_hub.py b/gns3server/compute/builtin/nodes/ethernet_hub.py
index 5aa95b32..ebc561ec 100644
--- a/gns3server/compute/builtin/nodes/ethernet_hub.py
+++ b/gns3server/compute/builtin/nodes/ethernet_hub.py
@@ -17,7 +17,6 @@
 
 import asyncio
 
-from ...error import NodeError
 from ...base_node import BaseNode
 
 import logging
diff --git a/gns3server/compute/builtin/nodes/ethernet_switch.py b/gns3server/compute/builtin/nodes/ethernet_switch.py
index 0d0119ff..523c3d01 100644
--- a/gns3server/compute/builtin/nodes/ethernet_switch.py
+++ b/gns3server/compute/builtin/nodes/ethernet_switch.py
@@ -17,7 +17,6 @@
 
 import asyncio
 
-from ...error import NodeError
 from ...base_node import BaseNode
 
 import logging
diff --git a/gns3server/compute/builtin/nodes/nat.py b/gns3server/compute/builtin/nodes/nat.py
index 1d7557cd..59c8f072 100644
--- a/gns3server/compute/builtin/nodes/nat.py
+++ b/gns3server/compute/builtin/nodes/nat.py
@@ -16,7 +16,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import sys
-import asyncio
+
 from .cloud import Cloud
 from ...error import NodeError
 
diff --git a/gns3server/controller/project.py b/gns3server/controller/project.py
index d6fa2fba..244cc9a4 100644
--- a/gns3server/controller/project.py
+++ b/gns3server/controller/project.py
@@ -946,10 +946,11 @@ class Project:
             raise aiohttp.web.HTTPConflict(text="Cannot duplicate node data while the node is running")
 
         data = copy.deepcopy(node.__json__(topology_dump=True))
-        # Some properties like internal ID should not be duplicate
+        # Some properties like internal ID should not be duplicated
         for unique_property in (
                 'node_id',
                 'name',
+                'mac_addr',
                 'compute_id',
                 'application_id',
                 'dynamips_id'):