Vb.net sendkeys, letters duplicate?

In your app settings (app.config in a Visual Studio solution, or <myapp>.exe.config when located side by side to the application), add the following as child of the <configuration> element:

<appSettings>    
    <add key="SendKeys" value="SendInput"/>    
</appSettings> 

If that doesn't work, try:

<appSettings>    
    <add key="SendKeys" value="JournalHook"/>    
</appSettings> 

Source: SendWait() [MSDN]

"... As a result, the SendKeys class may behave differently on different operating systems ..."