There is not so much difference between the two formation.
In a 4-4-2 Martinez will play further than Marchisio it's sure, so doesn't matter if we call it 4-3-3 or 4-4-2 or even 4-3-1-2.
Probably it's just a lopsided 4-4-2 wich in Martinez/Krasic play further than other midfielders.