  We consider the production and scattering amplitudes of heavy mesons in a
situation, where there are two closely spaced narrow resonances, which
structure we refer to as a diresonance. Assuming strong overlapping of the
resonances coupled to common channels, it is found, using the unitarity and
analyticity constraints, that the production amplitudes in different channels
should have similar behavior with energy. In particular the ratio of the
coefficients for each pole contribution to the production amplitude is fixed at
-1.
