+RL_DG/orcl/onlinelog/redo3b.log is the alias here. The 'real' file which ASM has internally created for your alias is +RL_DG/orcl/onlinelog/group_3.257.831130475
All filenames in ASM are created supposedly with OMF. When you manually specify a name , ASM will create the actual file with system generated file name. spfile creation in ASM is a classic example for this.