Hello adnil444,
You can use the steps below to edit a contact entry:
In the Contacts app
, assign a photo to a contact, add a pronunciation, pronouns, change a label, add a birthday, and more.
1. Tap a contact, then tap Edit.
2. Enter or update their contact information.
3. When you’re finished, tap Done.
You can also find those steps in this resource: Edit contacts on iPhone - Apple Support
You may also want to check for any extraneous or duplicate contact entries that have the same phone number or email address.
Should that still persist, are you syncing your contacts with multiple email accounts? You can check on that under the Settings > Contacts > Accounts menu: Manage and delete contacts on your iPhone or iPad - Apple Support
Let us know, and we'll keep moving forward from there.