You may find that the first paragraph (or more) of a long text box on a Blank Slide gets duplicated when previewed or published if the text box contains more than 3800 characters.
This is a known issue. You can correct it in one of the following ways:
- Reduce the text to 3800 characters or less.
- Split the text between two or more text boxes, so that none of the text boxes contains more than 3800 characters. Then align the text boxes on the slide, so that they appear to be a single, continuous text box.