Close. DUO's use the 5.4 tech and the 454 mutants use 454 tech both of which are available in both the Titans and the Mutants
DUO's have a 5.4 barrel. The 454 Mutant has a 454 barrel. Both are 2 piece. Follow? There are also Titans with 5.4 barrel (i.e. 2011 White Titan Resmondo) and also Titans with 454 barrel (ie 2012gray and yellow 454 Titan)
I believe 5.4 and 454 are both titan tech, perhaps I'm wrong though.