We cannot merge profiles and the reviews left by other users on both profiles. There are a few things you can do to let your buyers/sellers know your past and new reviews on both profiles belong to a single user.
If you decided to permanently switch from Profile 1 to Profile 2 and want to confirm that the older one (Profile 1) belongs to you, you can:
Method 1. Log in via your older account (Profile 1) and place the URL to your new profile in the bio. This way, users who want to do business with you can trust you based on your past reviews.
Method 2. Add a “Movedto” or “Now” indicator along with the new address to your profile nickname on Profile 1. This may look ugly, but it serves the purpose confirming you have logged in from the older address to prove the ownership.
Method 3. Update your banner image on the older profile (Profile 1) redirecting users to the new (Profile 2).