How to import data in CRM on Demand through front-end.

Hi,

I'm try to import an opportunity through front-end but getting an error. Can some one help, how to get the record through in CRM ? How to load bulk opportunity in CRM ?

Error : More than one associated 'Customer Name' record exists with value 'Amit Electric Europe B.V' for the import field 'CUSTOMER_NAME'. Since this information is part of the unique identifier for Opportunity imports, the record has been rejected.

Here is the map file , I've made for the mapping of fields.

"Oracle CRM On Demand Field","Import File Field"

"Account","Customer Name"

"Name","Opportunity Name"

"ZText_38","QUOTE #"

"ZCur_3","CURRENCY_CODE"