We can use more than one DockingManager in our windows by splitting a Grid or StackPanel into rows/columns. Then we can place DockingManager in each rows/columns of the Grid or StackPanel.

[XAML]

<Window x:Class="WpfApplication1.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:syncfusion="http://schemas.syncfusion.com/wpf" Title="DockingDemo" WindowState="Maximized">
<Grid>
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition />
</Grid.RowDefinitions>
<syncfusion:DockingManager DockTabAlignment="Left" Grid.Row="0">
<ListBox syncfusion:DockingManager.Header="ListBox1 of Top" syncfusion:DockingManager.SideInDockedMode="Left" syncfusion:DockingManager.DesiredWidthInDockedMode="300">This is listBox1 of Top</ListBox>
<ListBox syncfusion:DockingManager.Header="ListBox2 of Top" syncfusion:DockingManager.SideInDockedMode="Right" syncfusion:DockingManager.DesiredWidthInDockedMode="300">This is listBox2 of Bottom</ListBox>
<StackPanel><Label Content="This is the client area of upper grid"></Label>
</StackPanel>
</syncfusion:DockingManager>
<syncfusion:DockingManager DockTabAlignment="Left" Grid.Row="1">
<ListBox syncfusion:DockingManager.Header="ListBox of Bottom" syncfusion:DockingManager.SideInDockedMode="Left" syncfusion:DockingManager.DesiredWidthInDockedMode ="300">This is listBox1 of Bottom Gride</ListBox>
<ListBox syncfusion:DockingManager.Header="ListBox2 of Bottom" syncfusion:DockingManager.SideInDockedMode="Right" syncfusion:DockingManager.DesiredWidthInDockedMode="300">This is listBox2 of Bottom</ListBox>
<StackPanel> <Label Content="This is the client area of bottom grid"></Label>
</StackPanel> </syncfusion:DockingManager> </Grid>
</Window>