Can you please explain how to connect them?
I am sure it is not parallel connection ( as we will end up with 12v again ).
Of the three leads in the secondary of each transformer only the centre tap could be distinguished. The remaining two are identical. I guess that the voltages in the two leads are 180 degree out of phase(am I right?) How to obtain 24-0-24 from the six leads? How should I distinguish the leads of same phase and opposite phase? Will it matter when connecting them?