Hi Sumaira,
Don't worry, you won't lose any data.
The 'display name' is only used in the end user interface to give the user a friendly name. The fields stored in the backend use the 'name' attribute as the field name.
Once the field is created, the value of the 'name' attribute cannot be modified.
So, you have multiple 'display name' duplicate fields, because their 'name' attribute is actually different, and changing 'display name' will not affect the 'name' attribute, so it will not affect the data.
