If one watermark is good, are more better?

Invisible watermarks are not all alike. Different techniques are used to embed different types of watermarks into digital media objects to accomplish different goals. Some watermarks are intended to robustly carry ownership information; some are intended to carry content-verification information; and some are intended to convey side information, or captions. Some opportunities to employ multiple watermarks to convey multiple sets of information, intended to satisfy differing or similar goals, are examined. Problems presented by the insertion of multiple watermarks are discussed. Progress towards developing techniques that embed multiple watermarks into an image are also presented.