FT AC but already signed internship contract

I cannot do both as the FT program starts in the middle of my internship. The FT bank HR knows about this, but still want me to show up for the AC. I can't figure out why, because I know for sure I won't come back on my word and signature for my internship. Is it possible they don't care about my traveling expenses and they just want to establish a first contact maybe for the future ? Because if I were the bank I would never invite someone who is already "employed" by another bank.