” Are there actually identical state and federal charges for any given crime? “
In many cases there are because States cannot enforce fed law. However, to simply saw State law is fed law won’t stand the challenge.
The Fifth Amendment says that no person shall be subject for the same offense to be twice put in jeopardy of life or limb. Therefore state and federal crimes must be different or they cannot try a person twice for the same crime. Thats why in the Rodney King case the police were first tried for assault crimes by the state then later of violating the civil rights of Rodney King by the feds. I dont see how this law changes anything unless the presidential pardon were to occur before a trial on federal charges were brought, as in Fords preemptive pardon of Nixon.