ghost band

Wiktionary

1. n. sciences Any spurious results clustered together, outside of normal expected ranges (as in a plot of recorded energy values, with an inexplicable blot, marring the clean expected results).
2. n. biology A large band or stripe that appears on a developed gel as a wide halo with no specific, distinguishable signal. Ghost bands are a common problem in western blot analysis.
3. n. entertainment Impersonators of a well-known band hired to perform while the real band members are elsewhere.