I saw something like this recently in a little different context. In the output of a babel block I saw the empty table get inserted around the results. It only happened in one file, and I didn't notice if there was a user-error. I can't reproduce it at the moment, and didn't spend any time tracking it down. If I see it again I will see if I can track anything down.
I am using Org mode version 9.2.1 (9.2.1-23-g126a37-elpaplus @ /Users/jkitchin/vc/jkitchin-github/scimax/elpa/org-plus-contrib-20190218/)
John
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Professor John Kitchin
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803