Using the command line:
"xsd.exe" "OFX 2.1.1 schema/OFX2_Protocol.xsd" /c /namespace:OFX /nologo"
The resulting C# source file fails to build with these errors:
D:\blah\OFX2_Protocol.cs(19,6): error CS0579: Duplicate 'System.CodeDom.Compiler.GeneratedCodeAttribute' attribute
D:\blah\OFX2_Protocol.cs(20,6): error CS0579: Duplicate 'System.SerializableAttribute' attribute
D:\blah\OFX2_Protocol.cs(21,6): error CS0579: Duplicate 'System.Diagnostics.DebuggerStepThroughAttribute' attribute
D:\blah\OFX2_Protocol.cs(22,6): error CS0579: Duplicate 'System.ComponentModel.DesignerCategoryAttribute' attribute
D:\blah\OFX2_Protocol.cs(23,6): error CS0579: Duplicate 'System.Xml.Serialization.XmlTypeAttribute' attribute
D:\blah\OFX2_Protocol.cs(24,6): error CS0579: Duplicate 'System.Xml.Serialization.XmlRootAttribute' attribute
A similar XSD schema, which I copied from the OFX2 schema then trimmed down to the useful bits that I wanted, generates a C# file which builds just fine, yet has all the same attributes as the full schema's C# representation.
Any idea why? Is the OFX schema broken? Is xsd.exe broken? Is C# broken? Am I broken?
Ok, this answer is a long time coming...
I just ran into the same issue. The problem wasn't in foo.cs, but in foo.designer.cs. You have to remove the duplicate attributes in the second class.
C# should either allow duplicate attributes accross partial classes, or fix xsd to omit attributes in all but the .cs file.