It is recommended to copy the ORACLE_HOME when you are using RMAN/Hot Backup to create the database on target.
See 5.1 Refreshing a Target System
2. If the RDBMS ORACLE_HOME or the database needs to be refreshed, copy the database node file system. If refreshing the database, be sure to refresh the ORACLE_HOME at the same time.
This actually make sure any ORACLE HOME patches that you have applied in Source also gets migrated to target (you can ofcourse re apply them in target but that requires additional downtime and effort). And for this running adpreclone dbtier is mandatory so that the Cloning Driver Files, Scripts, Templates gets created that will be used in target during,
adcfgclone dbTechStack(Check Section 5.7 Cloning the Database Separately).
However if you are not copying the ORACLE_HOME and using a target ORACLE HOME as is and using RMAN/Hot Backup only to duplicate database, adpreclone dbtier on Source is not really required.
Thank you. That clarified my confusion.