stop duplicates with auto increment

[ana muslimon]

I have simple mysql table : id [auto increment] - name - details

I want to stop duplicates records, but i can't do that

because when i insert new recrod (even with same old record), it takes new id , and then it become unique record

I wish i could explain my problem well

ex.
id name details
10 a abc
11 a abc


Thanks in advance