Is it ok to run uglify on an already minified file?

[Naresh Bhatia]

I am using the grunt-contrib-uglify plugin to uglify the JS files in my project. One of the files happens to be a 3rd party library that is already minified. When the build is trying to uglify that file, it hangs. So the question is: is it ok to uglify an already minified file? Or should I set up my build not to uglify minified files? What's the best practice?

Thanks.