When you receive a second enquiry from the same person, about the same date/event, you have two options

1. Update the original enquiry with any additional details from the new second enquiry and delete the second enquiry.

2. Move it to Duplicate Enquiry. You can create a Lost inquiry stage called Duplicate Enquiry and move it there. You should do this if you want to know that they inquired twice going forward - but you do not have to worry about the inquiry showing as an active inquiry.