Our team was surprised to find that there was not a merge profiles function on the tool. This was a feature of Campaign Classic, however we found that there are many data issues as a result of not having that function.
We have thousands of duplicate profiles on our org's instance of ACS. The unique identifier was not set as the email originally and now we have the issue of users unsubscribing and still being on the email communications because they have several profiles under the same email address in our system.
I had heard rumors that this was going to be an addition to one of the updates, but I have yet to see any official statements on that function. I would think this is a basic need across all organizations.
Please let me know if there is any development on this!