Category WordPress default widget title display twice at WP 4.2

Hello,

After updated to WordPress 4.2, my category default widget title displaying twice. I have 4 sites using this widget so i'm pretty sure this is a bug of WordPress.

I tried to find the solution at http://www.wordpress.org/support but it seems no one using this widget.

Could you help me delete one titile? (you can try it on your site or using grant access to take a look one of my site).

Thanks,
Tuan.