diff --git a/src/modules/Elsa.Workflows.Management/Features/WorkflowManagementFeature.cs b/src/modules/Elsa.Workflows.Management/Features/WorkflowManagementFeature.cs
index a46f191ed..016bdb488 100644
--- a/src/modules/Elsa.Workflows.Management/Features/WorkflowManagementFeature.cs
+++ b/src/modules/Elsa.Workflows.Management/Features/WorkflowManagementFeature.cs
@@ -241,6 +241,7 @@ public class WorkflowManagementFeature : FeatureBase
             .AddNotificationHandler<DeleteWorkflowInstances>()
             .AddNotificationHandler<RefreshActivityRegistry>()
             .AddNotificationHandler<UpdateConsumingWorkflows>()
+            .AddNotificationHandler<ValidateWorkflow>()
             ;
 
         Services.Configure<ManagementOptions>(options =>
diff --git a/src/modules/Elsa.Workflows.Management/Handlers/Notification/ValidateWorkflow.cs b/src/modules/Elsa.Workflows.Management/Handlers/Notification/ValidateWorkflow.cs
new file mode 100644
index 000000000..4e3ed5258
--- /dev/null
+++ b/src/modules/Elsa.Workflows.Management/Handlers/Notification/ValidateWorkflow.cs
@@ -0,0 +1,31 @@
+using Elsa.Mediator.Contracts;
+using Elsa.Workflows.Management.Models;
+using Elsa.Workflows.Management.Notifications;
+using Elsa.Workflows.Models;
+
+namespace Elsa.Workflows.Management.Handlers.Notification;
+
+public class ValidateWorkflow : INotificationHandler<WorkflowDefinitionValidating>
+{
+    public Task HandleAsync(WorkflowDefinitionValidating notification, CancellationToken cancellationToken)
+    {
+        var workflow = notification.Workflow;
+        var inputs = workflow.Inputs;
+        var outputs = workflow.Outputs;
+        
+        ValidateUniqueNames(inputs, "inputs", notification.ValidationErrors);
+        ValidateUniqueNames(outputs, "outputs", notification.ValidationErrors);
+        
+        return Task.CompletedTask;
+    }
+    
+    private void ValidateUniqueNames(IEnumerable<ArgumentDefinition> variables, string variableType, ICollection<WorkflowValidationError> validationErrors)
+    {
+        var duplicateNames = variables.GroupBy(x => x.Name).Where(x => x.Count() > 1).Select(x => x.Key).ToList();
+        if (duplicateNames.Any())
+        {
+            var message = $"The following {variableType} are defined more than once: {string.Join(", ", duplicateNames)}";
+            validationErrors.Add(new(message));
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/modules/Elsa.Workflows.Management/Notifications/ValidateWorkflowRequest.cs b/src/modules/Elsa.Workflows.Management/Notifications/WorkflowDefinitionValidating.cs
similarity index 100%
rename from src/modules/Elsa.Workflows.Management/Notifications/ValidateWorkflowRequest.cs
rename to src/modules/Elsa.Workflows.Management/Notifications/WorkflowDefinitionValidating.cs