If you would consider doing it in workaround method here's how I did it:
Export your polygon as MapInfo file
Calculate centroids with Vector > Geometry Tools > Polygon Centroids
Export centroids as MapInfo File
Remove all unneeded info from Centroid MIF file, leave just coordinates
In your polygon MIF file add information that you have 2 more columns (x and y/lat and long) don't forget to update column count information.
In your polygon MID file copy all columns from centroid MIF file (excel will help here)
There might be a shorter/direct way to do this, but maybe my answer will help you.