You can win two of the three categories in one of these combinations:

1) Win "Top Photographer" & "Guru's Pick"

2) Win "Top Photo" & "Guru's Pick"

This is done to avoid cases where a single member 'sweeps' all the prizes (since "Top Photographer" usually has the photo with most votes). 

Secondly, the "Guru's Pick" is done by using the same voting system as the users so they don't know who they are picking.