Ederson Peka

With this plugin, you can create as much “sidebars” (widget areas) as you need, and assign them in a per-page basis. (It’s only useful if your theme supports “sidebars”.)
WARNING: Updating from versions prior to 0.2.5 requires new set up.

Unlimited Page Sidebars

This plugin does exactly what it needs to and always works. It's great.

Does exactly what it needs to!

Assign one specific widget area (sidebar) to each page.

Andrico

A wonderful plugin to easily create many custom sidebars. These sidebars can then select in the creation of a post / page / custom post type / category / taxonomy. We give an order, and select several at once. 
You will see all active sidebars instead of seeing just one.
VISIT https://wordpress.org/plugins/advanced-widgets/
Español:
Un maravilloso plugin para poder crear fácilmente muchos sidebars. Estos sidebars luego los podremos seleccionar en la creacián de un post / page / custom post type / category / taxonomy. Podremos darle un orden, y seleccionar varios a la vez. 
Se verán todos los sidebars activos.
VISITAR https://wordpress.org/plugins/advanced-widgets/

Multiple Sidebars

A wonderful plugin to easily create many custom sidebars. These sidebars can then select in the creation of a post / page / custom post type / categor …

Unlimited Page Sidebars vs Multiple Sidebars