Using two versions of the density functional theory (DFT), namely B3PW91/TZVP and DFT M06/TZVP model chemistries, a quantum-chemical calculation of the molecular structures of potential isomeric [benzo]annulated derivatives of porphyrazine - cis- and trans-di[benzo]porphyrazines containing deuterated groups (ND) at positions 21 and 23 - was performed. As a result of these calculations, it was established that the first of these compounds can exist in the form of four, while the second - in the form of two isomers, differing from each other in the mutual orientation of the deuterium atoms bonded to the nitrogen atoms. The main parameters of the molecular structures of these (D,D)-isomeric compounds, as well as the values of their total energies, standard enthalpy, entropy and Gibbs energy of formation are presented. The relative total energies of all the compounds under consideration were calculated, which revealed that the most stable of the deuterated di[benzo]porphyrazines is the (D,D)-isomer with trans-orientation of the deuterium atoms bonded to the nitrogen atoms, whereas the (D,D)-isomers with cis-orientation of the deuterium atoms have significantly higher total energies and, consequently, much lower stability. It was also noted that for each of the di[benzo]porphyrazines, the (D,D)-isomer is more stable than the corresponding (H,H)-isomer. The key parameters related to the molecular and electronic structures of di[benzo](D,D)porphyrazines, namely, bond lengths, bond and non-bonded angles, and to the data of their NBO analysis, were determined, and it was noted that they are virtually identical to those for di[benzo](H,H)porphyrazines similar in structure. Good agreement was also noted between the calculated data obtained using the two above-mentioned DFT model chemistries.