Ошибка XAML: "Свойство" VisualTree "установлено более одного раза"

Я пытаюсь поместить две сетки в DataTemplate.

Я получаю следующую ошибку с моим кодом, показанным ниже.

Ошибка: "Свойство" VisualTree "установлено более одного раза"

<DataTemplate x:Key="PareoItemTemplate">
    <Grid x:Name="gridColorEjercicio" Height="100" Width="350" Background="#FFF0F0F0" Margin="-11,0,0,0">
        <StackPanel Margin="0" Orientation="Vertical" HorizontalAlignment="Center" VerticalAlignment="Center">
            <StackPanel Margin="0,10,15,0" Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Center">
                <TextBlock HorizontalAlignment="Center" TextWrapping="Wrap" Text="{Binding letter}" FontSize="24" FontFamily="Resources/Fonts/Programa Tutorias Bold.ttf#Programa Tutorias" Foreground="Black" VerticalAlignment="Center"/>
                <TextBlock TextWrapping="Wrap" Text="{Binding option}" FontSize="24" FontFamily="Resources/Fonts/Programa Tutorias Bold.ttf#Programa Tutorias" Width="253" Foreground="Black" HorizontalAlignment="Center" VerticalAlignment="Center"/>
            </StackPanel>
            <Grid VerticalAlignment="Center" Margin="5,10,5,0" HorizontalAlignment="Center">
                <Image Source="{Binding imageURI}" />
            </Grid>
        </StackPanel>
    </Grid>
    <Grid x:Name="gridPareoColorEjercicio" Height="100" Width="350" Background="#FFF0F0F0" Margin="-11,0,0,0">
        <StackPanel Margin="0" Orientation="Vertical" HorizontalAlignment="Center" VerticalAlignment="Center">
            <StackPanel Margin="0,10,15,0" Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Center">
                <TextBlock HorizontalAlignment="Center" TextWrapping="Wrap" Text="{Binding letter}" FontSize="24" FontFamily="Resources/Fonts/Programa Tutorias Bold.ttf#Programa Tutorias" Foreground="Black" VerticalAlignment="Center"/>
                <TextBlock TextWrapping="Wrap" Text="{Binding option}" FontSize="24" FontFamily="Resources/Fonts/Programa Tutorias Bold.ttf#Programa Tutorias" Width="253" Foreground="Black" HorizontalAlignment="Center" VerticalAlignment="Center"/>
            </StackPanel>
            <Grid VerticalAlignment="Center" Margin="5,10,5,0" HorizontalAlignment="Center">
                <Image Source="{Binding imageURI}" />
            </Grid>
        </StackPanel>
    </Grid>
</DataTemplate>

Ответ 1