Does this offer include two (2) BL1920B batteries + charger? (Description uses the term "battery, i.e. singular.)

Yes, includes two batteries and charger as shown in the photo. We will update our website to make this more clear. Thank you.(1) 18V LXT® Compact Brushless 1/2" Driver-Drill (XFD12Z) (2) 18V LXT® Lithium-Ion Compact 2.0Ah Battery (BL1820B) (1) 18V LXT® Lithium-Ion Rapid Optimum Charger (DC18RC) (1) Tool Case