Q: Can multiple NFS or SMB shares point to the same base folder?
A. Yes. There's no restriction on the folders pointed to by the SMB or NFS share. Both SMB and NFS are file-based sharing protocols and allow access to the data stored within the folder and subfolders the share points to.
These protocols don't change the underlying file system. Thus, having multiple shares, even different protocol shares, that point to the same base folder isn't a problem.