One SVM (Storage Virtual Machine), AKA vServer, can join to one domain as a one Cifs Server. The behaviour is like a Windows PC. Because you can only have one Cifs Server per SVM, you couldn't have the same cifs share name. You could create 2 different SVMs with the same cifs share name.
As gpablo stated, you can only have one CIFS Server per SVM (i.e. namespace). All shares in each SVM must have a unique share name. Your example would need to be two, separate SVMs and two separate CIFS servers (one for each SVM).
This is typically becoming the issues with migrations from 7-Mode to cDOT, where you have multiple vFilers or even two 7-Mode controllers where each controller has a CIFS share with the same name and trying to consolidate them into a single SVM (i.e. namespace).
That's probably the only thing I don't like about a single CIFS Server per SVM - the consolidation aspect (when namespaces can't change - i.e. having 20 different vFilers and you can't collapse them into one, unfortunately). There are ways to consolidate multiple vFilers or 7-Mode controllers into a single SVM, but even then still, it requires architecture changes in regards to shares, apps, etc... (to point to the new SVM name).
Now, if we could ever get multiple CIFS Servers in a single SVM (or dedicate a CIFS SVM LIF to a junction path)...that'd be awesome (but highly unlikely)