A family of Microsoft word processing software products for creating web, email, and print documents.
There's definitely a bug in there somewhere, but I'm seeing a somewhat different behavior.
When nonprinting characters are not displayed, the style separator acts like an ordinary paragraph mark, placing the caption body below the caption label. That's shown on the left.
When nonprinting characters are displayed, the caption body moves up to the same line as the label as expected, but then the duplicate appears as you described, shown on the right.
The duplicate doesn't print -- that's what tipped me to the role of the nonprinting characters.
It all works properly if the table isn't set to wrap text around it.
I'm using the Office Insider version of Office 2016, version 16.0.6769.2017, which is probably a newer build than yours. I'll pass this along in the feedback.