Yeah you're right: what I bought again was in fact another item which contained the same items I already bought in the past (costumes, in that case).
Just to explain: during E3 I remember Capcom saying they would have sold their remaining SFXT DLCs sooner than originally planned.
Straight after the event they released a patch for the game and this 'new' DLC costumes pack for all the characters (it had a new icon and it didn't replace the 2 previous separate packs) so I assumed - stupid me - it would have been the second batch of crossover outfits.
Sadly, I only found out myself re-buying the first two crossover packs combined, which I already got months ago.
Point is: since when you buy 'complete packs' the PSN usually locks out all the related stuff with the same contents in it - see Soldner-X 2, Motorstorm, L.A. Noire... - I just expected that crossover pack to be automatically locked out in case it was old, hence my mistake (I realised it contained stuff I already got after my purchase).
Sorry for the wrong statement and for derailing a bit, I just wanted to explain.