DoubleAnimation.Completed event triggered at the end of the Storyboard

Question

So I have a Storyboard that will run multiple animations one after each other (not all of them simultaneously) and in some of those animations I subscribe to the DoubleAnimation.Completed event. The animations run perfectly fine, but the Completed event of the animations are only triggered once the whole Storyboard is finished, not when the individual animation is finished (BeginTime of next animation). For example:

Storyboard storyboard = new Storyboard();

DoubleAnimation hideAnimation = new DoubleAnimation();
hideAnimation.Duration = TimeSpan.FromSeconds(0.5);
hideAnimation.BeginTime = TimeSpan.FromSeconds(0);
hideAnimation.From = 1.0;
hideAnimation.To = 0.0;
hideAnimation.Completed += new EventHandler(HideAnimation_Completed);
Storyboard.SetTarget(hideAnimation, grid1);
Storyboard.SetTargetProperty(hideAnimation, new PropertyPath(Grid.OpacityProperty));

DoubleAnimation showAnimation = new DoubleAnimation();
showAnimation.Duration = TimeSpan.FromSeconds(0.5);
showAnimation.BeginTime = TimeSpan.FromSeconds(0.5);
showAnimation.From = 1.0;
showAnimation.To = 0.0;
showAnimation.Completed += new EventHandler(ShowAnimation_Completed);
Storyboard.SetTarget(showAnimation, grid2);
Storyboard.SetTargetProperty(showAnimation, new PropertyPath(Grid.OpacityProperty));

storyboard.Children.Add(hideAnimation);
storyboard.Children.Add(showAnimation);
storyboard.Begin();

In this example HideAnimation_Completed will be called after 1 second (total duration of storyboard) and after HideAnimation_Completed is done, ShowAnimation_Completed is called.

Is was expecting HideAnimation_Completed to be called after 0.5 seconds and ShowAnimation_Completed after 1 second, not both after 1 second.

Those anyone knows if this an intended behaviour of WPF or am I missing something?

NOTE: The previous code is just an example to explain the problem I have. In my real program I have multiple animations that are dynamically generated and added into a global Storyboard at different parts of the the class. So the idea of starting each animation at the end of the previous one using the Completed event and UIElement.BeginAnimation method, is the last of my resources since that would involve modifying quite a lot of my code (and it would probably have a great effect over the performance of my application).