UpdatePanel ... How to show 2 different UpdateProgress messages

Hi,
My understanding of how UpdatePanels work might not be correct, but I'm trying to show 2 different messages at different points.
<asp:ScriptManager ID="ScriptManager2" runat="server"></asp:ScriptManager> <asp:UpdatePanel runat="server" ID="Panel"> <ContentTemplate> <asp:Button runat="server" Text="START" ID="btnStart" OnClick="btnStart_Click"></asp:Button> <asp:UpdateProgress runat="server" ID="PageUpdateProgress1"> <ProgressTemplate> Message #1... </ProgressTemplate> </asp:UpdateProgress> <asp:UpdateProgress runat="server" ID="PageUpdateProgress2"> <ProgressTemplate> Message #2... </ProgressTemplate> ...