Mr. Vikram Reddy, This is not a problem. I am married to a Indian women and her brother (who had the same middle name REDDY) had the same issue as yours when he took GRE in India. It seems according to Indian naming system "REDDY" is used a Last name, So I guess people in India address you as
"S. VIKRAM REDDY"
But in USA the way of addressing your name is different
You are most commonly (and the correct form) addressed as "VIKRAM REDDY SATHYA"
So your given name would be: VIKRAM REDDY
and family or surname would be: SATHYA
I have seen most of the people here in USA addressing themselves with First and Last name (just VIKRAM SATHYA) or commonly VIKRAM R. SATHYA.
I was told some people who immigrated earlier in 1950's and 1960's didn't exactly knew how to address as they have REDDY as there Family Name instead of Middle name. There are a lot of doctors in USA who go with the name Dr.REDDY, but the fact is there are a lot more doctors (80% or more, most immigrated after 1970) who use the correct USA naming format so if you were a doctor the correct naming format would be Dr. VIKRAM R. SATHYA or simply Dr. SATHYA (Not Dr.REDDY like the way its addressed in India)
So when you registered for the test your entry (below) is correct US format.
Name: VIKRAM
middle name: REDDY
surname: SATHYA
This is the correct USA naming format and you should see your name on all identity cards (when applying for SSN, Drivers License, US Green Card and US Passport) it must listed (correctly as)
Given Name: VIKRAM REDDY
Family/Last Name: SATHYA
Also you should see on Airline tickets (international when flying to or in USA) printed as
VIKRAM REDDY/SATHYA
