Duplicate contacts can be fixed fairly easily from your device. Since you posted this question in the BlackBerry forums, I will assume you have a BlackBerry device, although you do not say which one you have. For the purpose of this reply, again, I will assume you have one of the latest BlackBerry 10 devices.
First, go to Contacts and open it up. Select one of the duplicate contacts. At the bottom of the window, you will see a little pencil icon and a link icon, then the triple dot icon. Select the link icon to link the selected contact with the other duplicate contact. A new window will appear with your selected contact. Press the link plus icon at the bottom. Scroll down until you find the duplicate contact you want to merge with your original contact. Now, both profiles will show in the window. If that contact has more than one duplicate, simply press the link+ icon again and repeat selecting other duplicates. When you have all your duplicates selected, select Save at the top right and you are done. For more info, go to Five Tip Friday – BlackBerry 10 Contacts app | Inside BlackBerry Help Blog for help.
Hope this helps,