I test an assumption of the lock-and-key hypothesis that paired and complex copulatory organs may impede flexibility. I found no differences in ejaculate volumes (dpm) deposited by males in left versus right female storage organs of Centrobolus inscriptus involved in single, double and artificially-terminated matings. When the data for all matings were combined there was symmetry in spermathecal dpm values (left-right: X±SE = 48.11±126.1828; n=21). No significant differences between the left and right ejaculate volumes occurred (T=711.5, n =59, P=0.19). My findings partially support the species isolating lock-and-key hypothesis for explaining divergence in millipede genital morphology.