Interesting observation in JS

Hi Team,
In this link below:

if I print the output of following -

I get two “new tab”
but some for this : console.log(videoWindow.tabOpen());
I get only one “new tab”

If I create my own like this:
var newWin = new Window();

I get one “new tab”

Can anyone please explain why two " new tab" are showing up for those ?

Sorry guys, I found the location where the function was called twice. My bad.