This style is an oddity to be sure.  The bottom half of the jacket has a conventional coat-style zipper in the center, single-breasted style. The top has a six-button, double breasted panel.

This Hudson’s Bay point blanket example sold on ebay a number of years ago.

An ad from 1939 for a similar style, also made from Hudson’s Bay point blanket material. Marketed in Children’s sizes.

A German ad from the same time frame, courtesy Florian Kremers. Also made from striped blanket material, but not Hudson’s Bay. The model name “Eskimo” references what seem to be the Canadian origins of this unusual style.

http://blog.livedoor.jp/mcfly_store/archives/50731859.html
A modern reproduction of this style, by Freewheelers. This blends the styling of the blanket mackinaw originals, with that of hunting coats of the 1920s and 1930s, and throws in extra ’30s style zippers for good measure.