I don't know what you are referring to by the 2 year residency. ???
Residencies range from 3 years for FP, peds, IM...to 6-7 years for neurosurgery.
Like leukocyte said above, to do CT surgery, you have to complete a general surgery residency (minimum 5 years; some programs are 7-8) followed by a CT surgery fellowship (another 2-3 years). This may be changing in the future to a 3+3 program (meaning only 3 years gen surg then 3 years CT), but for now you still have to complete a full general surgery residency.