The error says cannot register duplicate name 'slideCanvas' in this scope. I can only assume that you have another control called 'slideCanvas' that is defined in your application somewhere. Have you tried searching through the entire solution for 'slideCanvas'?
Other than that, there are a few other issues that cause this exception:
- Declaring a control in the
Resources
section usingx:Name
instead ofx:Key
. - Trying to serialize a control that has code behind.
You could also try simply removing the names from the controls and binding to them to replicate whatever functionality you named them for.
If you still have a problem, please show the XAML that is causing the error when you try to deserialize it.