2 website

You mean you want to merge the content of both pages into one website?
Or do you want to merge both sites into one multisite installation?

You could try exporting the content from one and importing it into the other. Here are 2 articles about it:

Tools Export Screen

Tools Import Screen

You can also solve this with different migration plugins: https://wordpress.org/plugins/tags/migrate/

Before you do this, it is best to make a backup of both webs.