If you sync your contacts in several accounts on G5, chances are that there are some identical or duplicate contacts in your phone book. To merge contacts on LG G5 and avoid any duplicates, do as follows:
1. Open the Contacts app
2. Tap the contact you want to merge with another contact
3. One the contact's details page, hit the 3-dot button on the top right, followed by the Merge option
4. Now, tap the second contact.
5. Contacts are now merged in to one single contact. You can easily do the changes you want.
To separate already merged contacts, do as follows:
1. Open the Contacts app on your LG G5
2. Touch the 3-dot icon, followed by More and finally open the Manage Contacts option
3. Touch to open the Merge settings
4. Go to the Merged Contacts tab and hit the Separate button next to the contact you want to be un-merged.