i want to merge a Project field for duplicated leads during my import or with a makro later. 

Example: 

1) existing contact:

Company   Name   Project

Microsoft    Brad      Start

2) new field from excel sheet

Company  Name   Project

Microsoft     Brad     TEE

Now i don't want to have a duplicate entry with the same company and the same name. Instead of this there should be following:

Company  Name  Project

Microsoft    Brad    Start, TEE

Is this possible and with which custom post type? Or do i need a makro after the import for this? 

Thanks!

best, 

Matthias