Strange. Perhaps the China Masters is not invitational like the Danish Masters is. It is listed as a World Grand Prix event whereas the Copenhagen Masters is listed as an Invitational event.
There is also a China Open later in November, also a 6* World Grand Prix event. The China Open will be held in Guangzhou (in the south-east region near Hong Kong), while the China Masters will be in Beijing (at the north). The distance between the two is not much lesser than between Bangkok and Jakarta (and Kuala Lumpur and Singapore are nestled in between).
In previous years (and also this year), there were 2 China Opens in the ITTF (table tennis) calendar. The two opens were held at different locations with different title sponsors. So, maybe they're doing the same for badminton. But who's complaining? Not me ...