Whereas the 7.2 min 240 Np, first identified over 60 years ago, has been assigned conflicting configuration by various investigators, the 62 min 240 Np is assigned a "probable" configuration, deduced in each case by primarily focusing on just a single β-connected pair of levels in either 240 Np (β − ) 240 Pu or 240 U (β − ) 240 Np decay. We evaluate the level energies of physically admissible 2qp configurations in 240 93 Np 147 employing a three-step procedure, with experimental inputs at each step, and using a well tested two-particle rotor model with inclusion of residual n-p interaction and other contributions. This exercise clearly establishes that the 62 min 240 Np and the 7.2 min 240 Np isomers constitute a Gallagher-Moszkowski (GM) doublet corresponding to the two-quasiparticle (2qp) configuration 5 + {p5/2 + [642] ± n5/2 + [622]}0 + with J π K = 1 + 0 for the higher-lying 7.2 min isomer. This assignment is conclusively confirmed in a level-by-level analysis of data on 23 β transitions in these decays.Structures of a few other 240 Np levels populated in 240 U β decay are also discussed.