need help tracking multiple campaign responses
I am looking for suggestions about how to handle a problem.
We have a raw mailing list of about 3,000 people. We're not importing them all as leads yet.
We are mailing all 3,000 people something every month this year. Mostly they will receive a postcard, or an envelope containing a gift certificate voucher. To register for the gift they are directed to a Web page (a different page/form for each mailing). When they fill out the form (a Web-to-Lead form) they become a Lead in Zoho CRM.
We have added a custom field to our Lead form (and the Web-to-Lead form) which contains the name of a specific monthly campaign. So when Leads come in we can recognize which mailing they are responding to even if it's much later in the year.
The problem is that people might respond to multiple campaigns and we would like to track the number, as well as which specific campaign each individual responds to.
In other words, one person might respond to the January, March and July mailings. It's a single Lead/Contact so we don't want duplicate contact records for them, but we do want to know that they responded three time.
I'm new to Zoho CRM so I'm hoping someone with more experience can suggest a way to approach this problem. Or tell me that it's impossible.