mysql return unique rows

I have a table columns
name, city, pledgetype(2 choices), and a few others

Is there a way to pick unique where
name and city is the same but pledge is different? ( so i would have each person either show up once or twice)

Even better, would there be a way to put only 1 name and city unique and in the pledge field put all the different pledges from different rows from that person.