CD duplication or DVD duplication is different from CD/DVD replication. The two are different because, when you burn information onto a CD or DVD-R it is known as duplication whereas, when information is added onto a CD or DVD during the manufacturing process, it is known as replication.
CD and DVD duplication
CD or DVD duplication is when you copy some information on your computer onto a CD or DVD. This process is carried out simply by installing one of the many CD or DVD copying softwares. The software extracts the selected file from your computer and burns this information onto your CD or DVD. This process might take no more than ten to twenty minutes, and is mostly dependent on which speed you choose to burn your disc at. There is nothing wrong in burning a disc at high speed; it is only that there may be times when it may not copy certain things onto the CD or DVD. The speeds of burning a CD or DVD depend on the speeds that particular CD or DVD writer offers.
CD and DVD replication
CD replication or DVD replication on the other hand is the manufacturing process when exact replicas are created of a particular CD or DVD. The first step is to check if the client master (original copy) is not in any way corrupted. Then through an intricate process, a stamper is used to create replicas of the CD or DVD by stamping the exact information onto other discs with a thin aluminum coat. This creates an exact replica of the original copy. It may be further lacquered for additional protection before packaging.