Name Already Exists Exception Class
The exception that is thrown when you try to add a control to a Microsoft Office Excel workbook or Microsoft Office Word document at run time, but the name provided for the new control already exists in the workbook or document.
[System.Diagnostics.DebuggerNonUserCode] [System.Serializable] public sealed class ControlNameAlreadyExistsException : Microsoft.VisualStudio.Tools.Applications.Runtime.RuntimeException
You can add controls to Excel workbooks and Word documents at run time by using the Office development tools in Visual Studio. For more information, see Adding Controls to Office Documents at Run Time.