Jean-Christophe,
Prompted by your questions, I've added comments in my two previous posts trying to better explain that repeated values (if any) are part of what must "balance" between the red & blue cells. In the language of multisets, LoL says that the values of the digits in the two "balancing sets" (of cells added and subtracted) must be equal multisets. IOW, the balancing sets must have equal content -- including any repeated values. This has always been the meaning of LoL, but perhaps it needed some clarification.
