Compiler Error won't go away

Can't get rid of this error:

Compiler Error Message: CS0433: The type 'ASP.AdminHeader' exists in both

'c:\Windows\Microsoft.NET\Framework64\v2.0.50727\Temporary ASP.NET Files\sv\067e1f70\aa34abf2
\App_Web_wux8t4cr.dll'

and

'c:\Windows\Microsoft.NET\Framework64\v2.0.50727\Temporary ASP.NET Files\sv\067e1f70\aa34abf2
\App_Web_adminheader.ascx.f1b43d4f.gbqadzq7.dll'

Source Error:

Line 53:         <div id="pageLayout">
Line 54:             <div id="pageLayoutHeader">
Line 55:                 <uc1:AdminHeader ID="AdminHeader1" runat="server" />
Line 56:                 <asp:contentplaceholder ID="BreadCrumbsPanel" runat="server">
Line 57:               ...