You're the authority on your website content, so if you want to add the recommendations for one page onto another--go for it!
However, there is a bit of housekeeping you will want to keep in mind.
Let's use two pages. The original project was created for website.com/ogpage. Once you saw the results, you added the new copy to website.com/updatedpage.
You will not see any new recommendations for website.com/ogpage for a few weeks. You might still see new recommendations for website.com/updatedpage. And those recommendations might not use the new copy.
Both of those things will resolve after a little time.
Great, now how can I track this?
If you mark the project as complete, it will start tracking impressions, number of keywords, and clicks for that original page.
But you want to actually see results for the updated page. Here's a workaround.
Like most hacks, it's not pretty or perfect, but it can help. You can force a second tracking page by going to All Pages and create a project using the page that got the new copy--website.com/updatedpage.
Make any project with it--it doesn't matter. Accept the project and mark it as complete so it can start tracking the same day that you finished adding the updates that you got from the /ogpage project. Then you can go back and delete tracking for /ogpage and look at tracking for /updatedpage. If you do it the same day as when you add your results, the before and after line will be accurate.