Cheat.dat is encrypted, usrcheat.dat is not. Use either/or for the R4, but not both at the same time. Most people use the cheat.dat on the R4 and only use the usrcheat.dat in it if they want to add codes not found in the official cheat.dat.....like online WiFi codes, which are NOT added to the official cheat.dat.
In the official dat, both the cheat.dat and usrcheat.dat contain the exact same codes, so don't put both in there at the same time or many codes will not show. You CAN use a cheat.dat and a usrcheat.dat at the same time, but only if the codes are different between them.