I've seen mention that they think the first landing site was much softer and that the final landing site is surprisingly hard. A lot of the science instruments turned on as soon as the lander thought it had landed the first time so they should have some measurements from 3 sites on the comet instead of one!
Also Philae was caught just after the first bounce by Rosetta's NAVCAM:
http://blogs.esa.int/rosetta/2014/11...first_landing/