DVD replication is the only method in order to achieve a true retail DVD product
. While duplication, or commonly referred to as "burning", of blank media is often convenient for low volume or fast turnaround, shops or internet retailers would only ever stock genuine manufactured product in other words those that have been produced via the DVD replication method.
In order to provide quantities that are 100% identical, DVD replication requires a glass master which is created from the original master and a stamper is grown. The discs are then all pressed from this stamper resulting in every copy being an exact replicate. Prior to the glass mastering, the original master is checked for errors via software such as Eclipse. Should errors outside of the tolerance level be present, glass mastering cannot proceed and therefore new original master would be required. Such checks are vital to be sure the DVD replication process can only provide product that will guarantee to play in all players.
Unlike DVD replication, any discs that are burnt will be different to each other and errors will be duplicated also. Therefore should an original have many errors that are undetected, duplicates are likely to have at least the same number of errors which is likely to result in playback problems for some players. Because discs produced via DVD replication are all identical and initially error checked, playability problems would not be an issue.
Retail outlets do not want excessive volume of returned faulty products and therefore it is common knowledge that duplicated discs would cause such problems. This is probably the main reason stores would only stock product made via DVD replication however there can also be quality concerns with the final appearance.
Most discs that are burnt will have a blue/purple base colour whereas professionally produced discs from DVD replication are silver. The surface print is either screen or litho printed rather than inkjet or thermal printed as is common for duplication resulting in sub standard quality. Sleeves and inserts for duplicated discs are also printed as either inkjet or digitally rather than the professional litho print that comes as standard with DVD replication.
In conclusion it is essential to be aware of problems with burnt media especially if you are planning a retail product. Your DVD can only have a chance to reach retail outlets if they have been produced via DVD replication.