Distinct SUM

Hi all,

I have a table with sales and their goal as per below:

Opp  Reps    Goal

1       Dave     500

2       Dave     500

3       Jane      500

The goal is the same for each rep ( $100 per week)

My question is how to write a measure to only count goal once for each reps?

So i can create a table like this:

Reps    Goal

Dave   $500

Jane    $500

Total   $1,000

I need to display total so I can't choose do not sum.

Can any one advice me? 

Thanks!

Irene