Yes! You can use as many plugins as you like!
Every POWr Plugin has a Unique ID. These IDs differentiate one version of a plugin from all others. Different IDs = different versions of the plugin.
But what if you want to use the exact same Contact Form on two different pages of your site? Just copy the exact same Shortcode or DIV from the Contact Form you've already created, and paste it inside a new page of your site. Using the same exact shortcode or DIV will create a clone. Editing one clone will cause identical changes to all other clones with that shortcode or DIV.