That seems like the wrong way to do it.

The post sentence spacing was never really treated as two consecutive spaces - conceptually, it's a single area of whitespace that is larger than the inter-word spacing.

If you especially cared about typesetting it correctly, you'd use a single   (or perhaps an  ).

The page actually has a stylesheet which sets white-space: pre-wrap, which tells the browser to preserve the double-spaces. It's like <pre> but with line wrapping enabled.