Just to note however, the prequel to Spartacus is listed as airing before season one due to it occurring prior to the events in said season. This is more of a logical arrangement than anything and imho makes the most sense.
As far as I know season 01 was 2010 and the speacials or prequel were 2011 and season 02 is 2012.
These aren't mutually exclusive
As hikaricore has commented we have these seasons/shows listed in chronological order for the storyline. So although the prequel was made and aired after the first season, it makes sense in many ways to list it before. The same way that Star Wars was made in the order Episode 4,5,6,1,2,3 but most people will list them as 1-6
And no order won't change unless the senior mods all have a sudden change of mind.
(N.B I've not actually seen Spartacus myself)