For bond dissociation energies (BDEs) of double and triple bonds, is number shown in tables for that second or third bond? Or all of them?
They're for the entire bond (so for a triple bond, all 3).

From Wikipedia, it can be defined as 


  The standard enthalpy change when [a bond, be it single, double, or triple] is cleaved by homolysis to give fragments A and B, which are usually radical species


So you get two fragments as your final state.