URGENT - Need Internship Offer Advice - ANYONE!!!

Okay… so I have two internship offers with start/end dates that overlap 2 weeks:

Internship offer 1 (return offer): September 5 - October 28

Internship offer 2 (my dream firm): October 17 - December 5

Point 1-

I really want to take advantage of them both career and network-wise, but that means I’ll have to request from the first company to start and end two weeks early. Is that rude? Should I be completely transparent? What are they likely to say? The biggest worry would be the onboarding, but I've already been through it all before and pretty much know the company and office inside out.

Point 2-

I know the first company really likes me and wants me long-term, I just don’t see myself working there post-graduation (it is not the company or people that I don’t like… the industry itself honestly does not excite me). I feel so guilty/selfish that I am taking up space or losing them money when they could be hiring another intern who is likely to stay with them for longer. This thought lingers even more now given I am a returning intern. Have any of you ever felt this before?

Would seriously appreciate advice/help from anyone...