I am new to RAC. While configuring local and remote listeners, I realized that our 2 node RAC has same spfile and control files on ASM storage. Though same control files for all instances might be understandable, the same spfile for both instances is not understandable. If both instances have to share same spfiles, how can I then configure local and remote listeners of both instances?

If I set local and remote listeners in our current configuration, then the local listener of both instances will be (assumed IP) and remote listener of both instances will be (again assumed IP).