I have a document with ONE space after each sentence. I would like to use
"Find and Replace" to change the single space to TWO spaces.

This is an easy problem for a human brain, but I'm not sure how to get
everything I want (and Not get what I DON'T want) with "Find and Replace".

If the sentence already has two spaces after it, I don't want to give it
three spaces.

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Example BEFO
Sentence one. The second. Here's the third. And finally the last.

Example AFTER:
Sentence one. The second. Here's the third. And finally the last.
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Here is one idea: I could do a two-step process.

Step 1: Replace "period space" with "period space space".
Step 2: Replace "period space space space" with "period space space".

Is there an easier way to do this? My document is over 60 pages long.

Thanks!

- John R. Baker