geraldalewis/coffee-script — comment on commit 6c9ded83c2ffd1bef3ddb0c9fa80ac53b3fd09a6
File: src/nodes.coffee line 1184
By davidchambers:

The wording of this message could be improved – *duplicate parameter names 'foo' are not allowed* doesn't read well. Perhaps something as simple as the following would be suitable?

throw SyntaxError "multiple parameters named '#{pname}'"