Those are African blue steels aka African hornets.
Your's or the DFS ones were being sold before as hornets by various people even though they didn't have the true alternating color of skirts like true hornets have.
http://blog.aquanerd.com/2014/03/re...ook-at-the-history-of-this-amazing-polyp.html
that was during the height of the hornet craze, every polyp that had a ring on the center, people were calling a hornet.