Yes. You can really see the offset here. The nut holding the old pulley on the shaft can be removed with an impact wrench. It still looks like, to me, the new pulley is pressed on - I really don't know. Even if it's removable, I suspect the end of the shaft would need threads to attach the old pulley - and those threads may not exist if that pulley is pressed on.
Did you buy the new generator from a local shop or mail order? If local, I'd take both in to show them. Perhaps they have a different new generator with a threaded shaft that would work (also ensure you compare tabs for mounting and match those also). If mail order from a jeep vendor, I'd definitely be on the phone with them to ask why they sent what they sent.