Imagine this scenario:
- a person signs up in public membership sign up page
- a membership and a contribution is created
- the same person, a while later, forgets that they have sign up and sign up again in the same public membership page.
- the current membership does not change (it's ok!) and a new contribution is created (mmmhh)
How can I inform the person that the membership has already been made?
Or, how do I search in CiviCRM for duplicate contributions for the same membership?
Update after Jay answer
When a contact pay twice the membership with the same email and in same period (year, fixed membership type plan in my own case) the membership is extended by a further 12 months. It would be optimal that the contact should be informed of the new end date and type of membership. How to do it?
To notify him and the organisation we could use CiviRules to send an email when "Membership is changed" trigger and "Membership End Date is changed". The problem is that the message template does not know which membership has changed, because it only has the 'latest membership' tokens...