a) Synthetic spectra of two identical dwarfs with T_eff = 8000 K, and mutually displaced by projected velocities of 0, 40, 80, 120, 160 and 200 km s^-1 to mimic a composite-spectrum binary (SB2). The continuous thick line represents the single-lined state, and the normal continuous line the maximum velocity displacement; the intermediate cases are drawn dotted. b) Similar to a), but the two otherwise identical stellar spectra differ in brightness by a factor of 2. For clarity our computed spectra represent only one-half of the orbit. In neither case do the composite spectra suggest a single metal-deficient object.