Previous speculations of this curious variant of the 1060 have been confirmed: this particular 1060 is actually based on the same silicon the 1070, 1070Ti, and 1080 are based on. Nvidia is likely getting rid of old Pascal and GDDR5X memory stock.
https://www.notebookcheck.net/Nvidia-s-new-GTX-1060-with-GDDR5X-memory-is-confirmed-to-use-the-same-die-as-the-1070-1070Ti-and-1080.361441.0.html