how to delete duplicate contacts on iphone xr

Contacts are neither stored locally on an iPhone nor in SIM. They are synced to an email account that you had Google, iCloud, AOL, Exchange, Outlook, Yahoo or any Other

1. How many Contacts account (email client server) you have?
2. What is your default Contacts Account?
3. Which email account you are using to store Contacts?

• See the GIF below for Contacts and Default Account

• Learn how to add an email account and make it default (Watch the GIF)
• This example is for Gmail but the process remains same for all Google, iCloud, AOL, Exchange, Outlook, Yahoo or any Other

It could be your iCloud Contacts too?

What do you see under Settings > Password & Accounts > Only Gmail?

If so

Log into gmail account through web browser and check your contacts. The google mail on a web browser has a unique way of identifying and deleting duplicates.