There is an important difference between L-110 and other HC-110 "equivalents" (Ilford makes one) and that is with respect to shelf life. HC-110 stock has a proverbially very long life. The reason for this is very straight forward. Water is necessary for oxidation to occur. Put a piece of iron in a completely moisture free environment and it will not rust. The HC-110 formulation contains no water. A mixture of glycols is used as a solvent for the developing agents and other chemicals. All the other developers that claim to be equivalent contain water and this is evident in their relatively shorter shelf like.
Since Kodak developed HC-110 to produce results as close as possible to those of D-76 there is nothing remarkable in Legacy's claim. Read Kodak's publication or
http://www.covingtoninnovations.com/hc110. One could merely use D-76.