MySQL Ignore Duplicate Insert on MULTIPLE Columns

I have an interesting one for the crowd. I need to insert data into a table, but ignore duplicates. This isn't the normal "IGNORE INSERT" question that I'm asking. The ignore must happen on multiple non-unique fields.

For example, let's say we have a table with first name, last name, address, birth date, and phone number. If first name, last name, birth date, and address are the same, then ignore the insert, as we can safely assume this is the same person. However, two different people can have the same first and last name, two different people can have the same birth day, and two different people can have the same address. For this reason, a unique index can not be placed on any column. I want to ignore only the SAME person. The rest of the information such as phone number need to be included in the insert if no duplicate was found.

The reason I need this is because I'm importing data from multiple sources, and some rows from these sources may be the same, so I want the result to be a combination of all sources with no duplicates.

I can do this programmatically (PHP) pre or post-insert, but it involves nested loops and is slow and ugly, so I'd rather not do it this way.

Let me know what you think. Thanks!