Editing one datagrid changes another
===

Having a weird problem with two WPF datagrids bound to separate ObservableCollections.

Here's my XAML:
<!-- language: xaml -->

    <Grid Name="gridShifts">
    <Grid.ColumnDefinitions>
        <ColumnDefinition/>
        <ColumnDefinition/>
    </Grid.ColumnDefinitions>
        <Custom:C1DataGrid Name="dgShift1"
                           HorizontalAlignment="Left" AutoGenerateColumns="False" CanUserAddRows="False" CanUserRemoveRows="False" CanUserReorderColumns="False" Grid.Column="0">
            <Custom:C1DataGrid.Columns>
                <Custom:DataGridTextColumn Binding="{Binding Path=Type, Mode=TwoWay}" IsReadOnly="True"  Header="Work Center"/>
                <Custom:DataGridTextColumn Binding="{Binding Path=RegularSkill, Mode=TwoWay }" Header="Personnel"/>
            </Custom:C1DataGrid.Columns>
        </Custom:C1DataGrid>
        <Custom:C1DataGrid Name="dgShift2"
                           HorizontalAlignment="Left" AutoGenerateColumns="False" CanUserAddRows="False" CanUserRemoveRows="False" CanUserReorderColumns="False" Grid.Column="1">
            <Custom:C1DataGrid.Columns>
                <Custom:DataGridTextColumn Binding="{Binding Path=Type, Mode=TwoWay}" IsReadOnly="True"  Header="Work Center"/>
                <Custom:DataGridTextColumn Binding="{Binding Path=RegularSkill, Mode=TwoWay }" Header="Personnel"/>
            </Custom:C1DataGrid.Columns>
        </Custom:C1DataGrid>
    </Grid>

And here's my code behind:

    

    public partial class MainWindow : Window
    {
        AMMData.Manpower mp = new AMMData.Manpower();

        public MainWindow()
        {
            InitializeComponent();
           
            gridShifts.DataContext = mp;
            dgShift1.ItemsSource = mp.WorkShifts[0].WCList;
            dgShift2.ItemsSource = mp.WorkShifts[1].WCList;

        }
    }


mp contains an ObservableCollection of WorkShifts, which contains an ObservableCollection of WorkCenter objects. 

My problem is that when I edit one datagrid, the other's values also change. I've tried setting the datacontext for both grids to their respective ObservableCollections, but the same thing happens. I feel like I'm moderately familiar with how WPF databinding works at this point, but I'm completely stumped on this issue. Thanks for any help.