When cache is enabled on first page load the system shows one caption, this is because the page has only just cached the first version of the page to the browser, assuming the cache plugin is enabled with browser caching enabled.

When the page is reloaded the jCaption code is added to the tags again and the caption is added twice because the code is in the tags twice and thus running twice. Of course the first one was cached to the browser then readied on page load as the cached version is loaded by the browser.

jCaption needs to be updated in order to prevent this happening when cache is enabled.