Question: When running a web application project, at seemingly random times a page may fail with a CS0433 error: type exists in multiple DLL's. The DLL's are all generated DLL's residing in the "Temporary ASP.NET Files" directory.

Answer: 
Got this problem when put a part of an aspx page into the separate user control. On my machine everything was fine, on the server got an error.

**Renamed the problem class and file.**

<http://support.microsoft.com/kb/919284> Method 2: Reorder the folders in the application is writing about possible circular references
You should define an alias for one of your references.

In your project file `.csproj` add the following item:

```
<ItemGroup>
    <Reference Include="temp1.dll">
      <Aliases>MyAssembly</Aliases>
    </Reference>
</ItemGroup>

```

After adding the above ItemGroup, `MyAssembly` will represent a root namespace that will contain all namespaces in the assembly `temp1.dll`.

Then you can have access to the type `foo`, which is located in `temp1.dll`, as follow:

```
using MyAssembly.foo;

```