As usual, Mkikaden is solid.
Even if this second skill were 1x, you now have a second 1x skill for a 2x total training time between the two of them where each skill individually gives you half the benefits of this one skill that requires the least possible training time of any skill in the game.
Furthermore, here is something I love about the Biology skill: right now, boosters are grossly underutilized in the game by most players, even the mass-produced Synth ones that have no side effects and are cheap to make and buy. One of the (admittedly lesser) reasons CCP started Evergreen rewards was to raise the profile and awareness of boosters other than cerebral accelerators. When players learn that the Biology skill can extend the life of cerebral accelerators and “other boosters”, they inquire what those other boosters are, and that helps get them hooked onto drugs. More EVE players need to use more drugs with more regularity; having a singular Biology skill promotes drug use. Having a singular Biology skill (which again, is 1x, this cannot possibly be emphasized enough) encourages drug use via raising awareness and making them more worthwhile to acquire and use.
Get hooked on drugs, kids! 
