We consider the possibility to use two-channel neutron monitor with long and short dead times for detection of neutron generation multiplicity spectrum. The method for determination of exact value of the neutron flux incident on the monitor surface is experimentally proved and the error caused by using the data with r = 1200 μs is estimated. Based on the data for the flare of 29 September 1989, the dynamics of one-fold neutrons delay relative to the complete incident flux is investigated.