Samsung
Move Contacts to Another Storage Location auf Samsung
On Samsung phones, contacts do not always live in one place. Depending on how a number was added, it might sit on the SIM card, in the phone's internal storage, or inside a synced account such as Google or Samsung Cloud.
This split becomes a problem when you swap SIM cards, remove an account, or simply want all contacts consolidated in one spot before a backup. Copying each contact by hand is slow and error-prone, especially with a large address book.
Samsung's Contacts app includes a dedicated tool for this. Open Tap on Contacts ➔ Open the Menu ➔ Tap on Manage contacts ➔ Tap on Move contacts.
Next, pick the source location with Select from where to move. Choose the entries you need and confirm with Select the desired Contacts and tap Done.
Finally, pick the target with Select where to move and tap on Move. The selected contacts are relocated, not duplicated, so the original entries disappear from the source storage once the move finishes.
If contacts still appear duplicated afterward, check whether the same entry also exists in a synced account, since account sync can recreate an entry that was moved off the phone.