Do ad copies keep the engagement of the original ads?

It depends on how the copy is created and where it’s launched.
​

In the Duplicate action settings, check Show existing reactions, comments and shares on new ads.
​

With the option enabled, the copy uses the same post as the original ad. This works the same way as creating an ad from an existing post in Ads Manager, so all reactions, comments and shares are kept on the new ad.
​

With the option disabled, the copy is created as a new post and starts without the original ad’s engagement.
​

In Stage, every ad is created as a new instance, so ads launched there start without engagement history.