Error using http-function post()

I also noticed when inserting into live collection - it created a new columns with a square bracket. Strange…Is this a bug? http://prntscr.com/jgeg71
Here is what I sent to the function: http://prntscr.com/jgegld
Here is the function: http://prntscr.com/jgegwq

Is there a way to create a record where the field is without the square bracket?