Why does pep8 suggest using two spaces in comments?
coding-style, pep8, python
Solution
Only those who authored the PEP can answer the "why" with any degree of certainty.
I've had a look at the standard library source code, and my conclusion is that this particular aspect of the style guide is not followed consistently: some standard modules follow it and some don't.
Until you pointed it out, I've never heard of the double space convention, and have never noticed anyone following it.
Problem
PEP-8 states: You should use two spaces after a sentence-ending period. In my usual refactoring, I am used to replacing such consecutive double spaces with a single one, thinking that this habit has come from the typewriter days (I have went through this Wikipedia page briefly). Also most of the times I have seen mono-space fonts being used for the programming, so it's much clearer than the other cases which can sometimes need 2 spaces to easily identify sentences. Is there any reason behind this being used in PEP-8?