Original sentence: Digital rights management schemes are often used to discourage duplication of digital media by preventing copying of content, which also has the effect of reducing its utility to paying customers who want to play their purchased material on multiple machines, or make backups.The reduced functionality leads to the situation where pirates have a better product, and pirated copies may be preferred over genuine ones
Edited sentence: Digital rights management schemes typically stop all copying of a purchased product (music, in the archetypal case), to keep buyers from making copies for their friends -- but this also keeps them from making copies for their own use, and can encourage them to find pirated copies of what they've already bought