My project in asp.net c# and gives this error online on server. what is this problem ..please reply me urgently

Server Error in '/' Application.

Compilation Error

Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

Compiler Error Message: CS0433: The type 'Gallery' exists in both 'c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\f3c0436d\59eacbb2\assembly\dl3\14716073\d2927f12_ce89cd01\App_Code.DLL' and 'c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\f3c0436d\59eacbb2\assembly\dl3\29d4192d\dcd26915_ce89cd01\App_Web_ndt049ne.DLL'

Source Error:


Line 110:
Line 111:    [System.Runtime.CompilerServices.CompilerGlobalScopeAttribute()]
Line 112:    public class gallery_aspx : global::Gallery, System.Web.SessionState.IRequiresSessionState, System.Web.IHttpHandler {
Line 113:
Line 114:        private static bool @__initialized;

Source File: c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\f3c0436d\59eacbb2\App_Web_gallery.aspx.cdcab7d2.ldq1sk0g.0.cs    Line: 112