overwriting details

hello all
im after some help please
my app is here creator.zoho.com/mosleypup/benchy/#
if you have a look at this you will see in the reults section there are users that have been added more than once. what im after doing is a user inputs there details and if they already have a record on the database it updates that record so i dont have 4 reults from the same user.
is this possible ?
can anyone please help me fix this ?
many thanks
moses