Just something I thought about :P
let's think about it this way:
Fed's Australian Open
= Djoko's Wimbledon
Fed's Roland Garros
= Djoko's Roland Garros
= Djoko's Australian Open
Fed's US Open
= Djoko's US Open
2003 & 2008 - First GS for each player
Both players won their first GS, and in their 'best' tournament of the four.
2004 & 2011 - First year of absolute Dominance
Both won 3 Slams in those year, and were more dominant than any other player on the tour. Also, the only Slam they didn't win was their worst Slam - RG. I know Fed's done it in 2004 which is of course right the next year after 2003, and Novak had a two year break, but oh well...
2005 & 2012 - A little less successful than the previous year
Only two Slams for Roger: His best one, and his second best. Novak has already won his best slam this year, so he now needs to win the USO :P
I'm kidding of course, but this is just interesting