%Warning-MODDUP: t/t_mod_dup_bad.v:13: Duplicate declaration of module: 'a'
                 t/t_mod_dup_bad.v:6: ... Location of original declaration
                 ... Use "/* verilator lint_off MODDUP */" and lint_on around source to disable this message.
%Warning-MULTITOP: t/t_mod_dup_bad.v:16: Multiple top level modules: 'b' and 'test'
                                       : ... Suggest see manual; fix the duplicates, or use --top-module to select top.
%Error: Exiting due to