Two master page with same cs

Friend,
I have two master page with same CS, everything is working fine expect publish, when I try to publish it through an error,
any one has any idea for this situation.

Error 27 The type 'MPmaster' exists in both 'c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\webstage1\9d60be9c\b26a541\App_Web_sut7koud.dll' and 'c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\webstage1\9d60be9c\b26a541\App_Web_zxyzdyi_.dll' c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\webstage1\9d60be9c\b26a541\App_Web_hmdc2hxt.10.cs
Shakti
 
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