Imports fail with non-unique column names

When an import file (csv) has two columns with the same name, only the values of the last column is imported. Feeds build and associative array per row, with the header name as key. This is the reason it fails when there are several columns with the same name. I've written a small patch that appends a counter number after the name if there are more than one row.

Source:

name = John
name = Johnny
surname = Doe

Destination before the patch:

name = Johnny
surname = Doe

Destination after the patch:

name = John
name2 = Johnny
surname = Doe