Can somebody please help how to avoid duplication of contacts while uploading a new spreadsheet generated through multiple marketing activities in SugarCRM 6.0 Community Edition !

There is a manual process of merging individual contacts if there is a duplication of a certain lead however this is highly impractical if we are talking about huge volumes of data. I posted this request long back on Sugar Forum but nobody ever responded, wondering WHY

I am looking for an automated way through which I could avoid creating multiple leads of the same name (whenever I upload a new spreadsheet) that are created through different campaigns while they are already present in my CRM Database.

I hope to hear from somebody soon ! I am stuck with this issue since a month

Kind Regards,
Jahnavi Ray
jray@smarteinc.com