In order to remove duplicate clients we will go to: 

System --> Tools --> Customer records consolidation

The next window will open. 

Where we will click on the magnifying glasses. 

Remember that both clients, must be registered in the system to be consolidated.

At the click a list will be opened with all the clients, we will click on the button  of the client Origin.

And in the same way in the Destination Registry. (The Origin Registry is the one we want to "remove" and the Destination Registry the one we want to "keep", will keep the mail, phone, accounts etc. from the Destination Registry, no matter how bad they are.)