[caption id="my-caption-id" class="my-caption-class" align="alignnone" width="399"]
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    My caption text
[/caption]

<div id="my-caption-id"
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     class="wp-caption alignnone my-caption-class">
    <img src="whatever.jpg" alt="whatever" width="399" height="600">
    <p class="wp-caption-text">My caption text</p>
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