Display name shows values other than first, last or nickname fields

[corre]

The Display Name field should suggest name options correlative with the formal name fields: First Name, Last Name and Nickname. Instead, the Display Name field is freely editable from the user profile edit page, making the Nickname field obsolete.

The Display Name field shown be affecting the Nickname field and not act as an independent name field.

How can I fix this at least in my website, rather than wait for the next version (if at all, this issue will be addressed)?

Thanks,
Ran