WPF TabControl's SelectionChanged event handler executing twice..!

Hi, I am having problems with an TabControl's event: SelectionChanged.

the first problem I had was that my event was raised many times, so I Added this to my code:

In my XAML:

<TabControlName="mainTabControl"SelectionChanged="mainTabControl_SelectionChanged">

void mainTabControl_SelectionChanged(object sender,SelectionChangedEventArgs e){if(e.SourceisTabControl){// do some}}

But, then I started having another problem which was because the event was trying to raise when the form wasnt loaded, so I added the following:

void mainTabControl_SelectionChanged(object sender,SelectionChangedEventArgs e){if(e.SourceisTabControl){if(this.IsLoaded){// do some  }}}

But my problem right now is that the FIRST time I try to change of tabItem the event raises TWICE and the selected tabItem remains the same, after doing that the event works as expected.

How Can I solve the last problem? Am I doing something wrong?