Find relationships between items in an Excel list

I have an Excel list that looks like this:

Project  ID
ABC      Al
ABC      Bob
ABC      Chad
DEF      Bob
DEF      Dick

I am trying to find a function so that I can only have the links between IDs. The final list would look like this:

Al Bob
Al Chad
Bob Chad
Bob Dick

In other words, you can see from the input that persons Al, Bob and Dick worked on project ABC. In my data, that means that they have a relationship (i.e. they worked on the same project). Thus, I would like to have one line per relationship.