You can add the second space by including it in the 'Enter formatting for number' field in that dialog. When the "Follow number with:" field is set to Space, you get a space but it doesn't show as a visible space (assuming you set your options to display spaces on screen like you should)

If you prefer, you can add multiple spaces in this field and set the Follow number with to Nothing.

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Andrew Lockton
Chrysalis Design, Melbourne Australia