Mine is 3.3lbs, it a 6s and 6s+ and probably the box to turn in 2 old phones for the iPhone forever discount. Either way I'm good, Friday can't come soon enough.
I ordered a 6s+ on launch then a 6s a couple days later. MyChoice has the package at 4 lbs even. First, I would be surprised if Sprint's logistics is good enough to get the phones shipped together and second, 4lbs seems really high?
Edit: I also did the iPhone Forever plan, so it may include the phone return boxes.