Random images on sidebar with 2 widget – ordering these

Hi! Let me see if I can explain what I need.
I was wondering if there’s any way for me to this:
I have 2 banners and these 2 banners need to be on my sidebar.
But, the order of those can’t be the same, I mean, when the Banner A shows first then Banner B, when I refresh the page this ordem should change, or, the Banner B appears above Banner A.
I tried to use some plugins of random images but none help me, because the ordem of theses banners, sometimes, are the same (Banner A and Banner A)

For example, the plugin I use was Random Banners and how I did it:

Widget Text 1:
Banners:
http://cronicasdasurdez.com/wp-content/uploads/2016/01/banner-260x260px-direito-de-ouvir.jpg
http://cronicasdasurdez.com/wp-content/uploads/2015/12/sonora_banner.jpg

Links:
http://www.direitodeouvir.com.br/display/?utm_source=cronicasdasurdez&utm_medium=banner&utm_campaign=teste7dias
http://portalotorrino.com.br/equipe-sonora/

Widget Text 2:
Banners:
http://cronicasdasurdez.com/wp-content/uploads/2015/12/sonora_banner.jpg
http://cronicasdasurdez.com/wp-content/uploads/2016/01/banner-260x260px-direito-de-ouvir.jpg

Links
http://portalotorrino.com.br/equipe-sonora/
http://www.direitodeouvir.com.br/display/?utm_source=cronicasdasurdez&utm_medium=banner&utm_campaign=teste7dias

Even I changed the order of those, sometimes, after reload the page, the same banners appears.

I need this:
– BANNER A
– BANNER B

Reload page

– Banner B
– Banner A

It is possible? I thought about “fix” the order of each widget, but I don’t know how to do it.

I hope someone can help me with this.
Thanks a lot,
Daniele