Any duplicate attribute overwrites a previously copied attribute. If you want to allow duplicates (for those attributes whose type specifies “AllowMultiple” in their definition), then you can also set the AllowMultipleAssemblyLevelAttributes.

The input assemblies are processed in the order they are specified. This option is mutually exclusive with specifying an attribute assembly, i.e., the property AttributeFile.

When an attribute assembly is specified, then no assembly-level attributes are copied over from the input assemblies

Command line option: /copyattrs

Default: false