The "2-electron-sensitization" follows the same principle as the HCO2-doping by scavenging a hole and finally releasing an additional Ag atom (though by different compound and reactions).

Whereas the "2-electron-sensitization" only works at the shell of the crystal and thus is only capable of scavenging those holes that make it that far, the Belloni-Agfa system is situated inside the crystal and thus will be much more effective.

Kodak put their system into production, Agfa did not...