Gracer vs Middle Earth themes

What is the difference between these two themes? It looks like "Gracer" (https://smthemes.com/gracer/) is just a later version of "Middle Earth" (https://smthemes.com/middleearth/). I'm not upset about it; Middle Earth needs newer support, but why not just upgrade Middle Earth instead of making a separate theme? Are these two different teams working on nearly identical themes?