  It is shown that the ratio of the production rates of the pairs (B+ B-) and
(B0 anti-B0) should experience a substantial and rapid variation with energy
within the width of the Upsilon(4S) resonance, crossing the value of one near
the center of the resonance. This behavior is due to an interference of the
rapidly changing with energy Breit-Wigner phase with the phase introduced in
the wave function of charged mesons by their Coulomb interaction.
