> What do you mean by "registers"?

A row.

A want that a combobox with two colunms has this apearence.

name of row of colunm1 - name of row of colunm 2

A want to use a '-' to separate the colunms.

For example: colunm first name and colunm last name. If a use ' ' to
separate the colunms, my result will "Helen Borrie" inside the combobox.
Then the user doen't know that exist more than one column there.