Templates - Duplicate Actions in Ribbon UI under certain circumstances

Hello Julien,
We have fixed this problem in version 10.2.5. For now, please use the following workaround:

C#
...  
static void winApplication_CreateCustomTemplate(object sender, CreateCustomTemplateEventArgs e)  
{  
            if(e.Context == TemplateContext.ApplicationWindow) {  
                MainForm mainForm = new MainForm();  
                mainForm.RibbonTransformer.BarItemAdding += new EventHandler<DevExpress.ExpressApp.Win.Templates.ActionContainers.BarItemAddingEventArgs>(RibbonTransformer_BarItemAdding);  
                mainForm.RibbonTransformer.Transformed += new EventHandler<EventArgs>(RibbonTransformer_Transformed);  
                e.Template = mainForm;  
            }  
}  
        static void RibbonTransformer_Transformed(object sender, EventArgs e) {  
            ClassicToRibbonTransformer transformer = (ClassicToRibbonTransformer)sender;  
            transformer.BarItemAdding -= new EventHandler<DevExpress.ExpressApp.Win.Templates.ActionContainers.BarItemAddingEventArgs>(RibbonTransformer_BarItemAdding);  
            transformer.Transformed -= new EventHandler<EventArgs>(RibbonTransformer_Transformed);  
        }  

        static void RibbonTransformer_BarItemAdding(object sender, DevExpress.ExpressApp.Win.Templates.ActionContainers.BarItemAddingEventArgs e) {  
            ClassicToRibbonTransformer transformer = (ClassicToRibbonTransformer)sender;  
            if(e.Group != null && transformer.FindBarItemLinkByCaption(e.Group.ItemLinks, e.Item.Caption) != null) {  
                e.Group = null;  
            }  
        }  
...  

You can subscribe to the CreateCustomTemplate event of the winApplication object either within the Program.cs file or in the construction or your WinApplication class descendant.
Please let us know if we can help you further.
Thanks,
Dennis