Not sure if bug...

...but I set it to the fsbugs e-mail anyway.

Let's start with this F# code:

The last function maps to C# as

Now change the initial F# line to be namespace rather than module...

File1.fs(9,18): error FS0755: The 'CompiledName' attribute cannot be used with this language element
File1.fs(15,18): error FS0755: The 'CompiledName' attribute cannot be used with this language element
File1.fs(19,18): error FS0755: The 'CompiledName' attribute cannot be used with this language element

So for comparison purposes, let's replace CompiledName with Obsolete, and see what we've built...

where I can't for the life of me see the difference.

This happens when building using the latest compiler release in either VS2008 shell or VS2010 shell; or from the command line using MSBuild for either .net3.5 or 4.