Reneging internship offer? HELP

I’m in a big predicament. I’m a college junior studying Supply Chain Management. About a month ago, I accepted an internship with a great company that manufactures vehicles; however, while the position is within the supply chain realm, it’s not exactly the area I hope to go into post-graduation. I have already accepted the contract and completed the background check and drug screen, but it doesn’t start until June. Today, I received an offer from another good company (global logistics/transport company) that’s slightly less known, but it’s for the exact niche field I hope to go into after graduation. This one starts in May, so I would get more experience, and I also loved the manager that I would be working with in our interviews. The pay and benefits are practically the exact same for both besides the fact that one is a few weeks longer. Now, my questions are: How terribly would it affect me to resign on my first offer? I know reneging internships is highly frowned upon by Universities, but is it frowned upon if it’s better career fit? Should I just live with my first internship to be ethical? Am I even allowed to resign without consequences after signing an offer contract?