I can tell you how to calculate the total number of people who received the information. I don't know how to distinguish the repeaters from the non-repeaters, though.
To calculate the total number of people who received the information:
1. Select Peter in the graph pane.
2. Right-click Peter in the graph pane and select "Select Subgraphs" from the right-click menu.
3. In the Select Subgraphs dialog box, click "The clicked vertex only", set "Levels of adjacent vertices to include in each subgraph" to 2.0, click Select, and then Close.
You have now selected Peter, his friends, and his friends' friends. To calculate how many people that is:
4. Right-click anywhere in the graph pane and select "Edit Selected Vertex Properties" from the right-click menu.
5. In the Vertex Properties dialog box, set "Marked?" to "Yes" and click OK.
This adds a "Marked?" column to the Vertices worksheet and sets the cell for each selected vertex to "Yes." To count the "Yes" cells:
6. In an empty cell somewhere in the Vertices worksheet, enter this formula:
That is the count of Peter, his friends, and his friends' friends.