convertTokenView overriding existing user details

[DevilsAutumn]

Hi, I'm trying to implement social authentication using google and github , i have an existing user model with first and last name fields. I created an account in normal way and want to connect google account with that account. The problem here is when i abm sending a POST request on auth/convert-token/ with google's access token it its overriding my first and last name and when i connect same account with github it is again overriding first and last name.
What i want is that none of the social accounts should overriding existing user details, What is the best way to do so?
Thank you in advance!