I checked up my old guild I progressed with during ICC. I knew we weren't good at all, but wowprogress says we have one world first. I saw many guilds which has festergut ranked as world 1 and then thought it's a bug. But what I realized is it's only my guild which seem to have the orange color.
Then I asked someone and they said the one with the orange is world first and the rest with the white is people who killed it on the same day and therefore all got rank 1.
What do you think? True or bug?