Double DLL exports when using .DEF file with alias

I use a .DEF file to build a Win32 DLL with VS-2015 (Intel compiler). The .DEF file looks like this:

EXPORTS a=my_func

The problem is that the DLL has two exports for the function and I'm not using any dllexport(...) stuff:

Ordinal Entry Point Name 1 0x00002160 a 2 0x00002160 my_func

How can I avoid this? I just want to export the functions with the name given in the .DEF file.