A restore over an existing database is equivalent to dropping the old DB and replacing it. It's not a merge, SQL discards the existing DB and completely replaces it with what's in the backup file.
Script the procedures before the restore (management studio, object explorer, right click the DB, tasks, Generate scripts, then work through the wizard
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)SQL In The Wild
: Discussions on DB performance with occasional diversions into recoverability
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