A common method of duplicating a product is called "clean room reverse engineering". This involves having two separate teams of engineers. The important thing is that these two teams never see each other, talk to each other, pass each other in the hallway, or have any contact whatsoever. Team A (or the dirty team) is sent to reverse engineer the original product (also called the target product). They take it apart, run tests on the components and the whole, and generally figure out what makes it tick. They then draw up their conclusion, as a set of complete specifications for the product, in a document called a Design Document. Their job is over; they are then dismissed. The design document is handed over to Team B (or the clean team). Using this document, they then reconstruct the product from scratch to do exactly the same thing that the original did.

This process is used to sidestep legal issues with reverse engineering a product with the intent of duplicating it. The dirty team has no intent of duplicating it and the clean team has never reverse engineered the product. It is important, for legal purposes, that the clean team has never seen or used the original product at all.

A well-known case of clean room reverse engineering involves the IBM PC. In 1982, the IBM PC was a widely-used computer. While various attempts to copy it had been made, these attempts all resulted in an imperfect copy that was similar, but not identical to the PC, and were unfit for many purposes. An engineer named Rod Canion decided to make money off the situation by forming a company called Compaq, which used the clean room procedure to clone the IBM ROM BIOS (the most important piece of the PC that was proprietary to IBM) and create the Compaq Portable PC.

Being not only 100% compatible with the IBM PC, but also cheaper, not to mention portable, made the Compaq very popular and sparked the whole PC clone industry.