From all the research I have done, I have never, ever, seen a Cuba Libre recipe which calls for Angostura, and generally, the proportions for rum to coke are more towards 1:3 (according to the International Bartender's Association, it's 5cl rum and 12cl coke) but of course, this is a matter of preference. Also, there is no muddling in a cuba libre, you just add 1cl of lime juice.

Now, I don't know who adds these recipes, but why is Angostura listed?