As I understood the "renegative double," it was sort of a concept similar to good-bad or a maximum overcall double (never understood that terminology), in the eraly days before people came up with those alternative solutions. Also, it was strangely limited to the specific instance of a negative double by Responder -- why is a mystery. But, nonetheless, the idea was that in this very auction, a double by Responder having shown hearts, and spades raised by advancer, the double was used to distinguish a weak raise to 3♥ from a strong raise to 3♥. Which was weak and which was strong I cannot recall. That idea then got expanded by a lot of people who play Montreal Relays to have Opener also make negative doubles ater the 1♦ response and intervention. However, that is really just an Opener's negative double. The "re-" in "re-negative double" means that the double happens twice, meaning open-overcall-double-advance-double. The utility of this approach has lost some merit, IMO, in that good-bad works better after spade intervention. In the event of heart intervention and a leap (1min-1♥-X-3♥-? or 1min-2♥-X-3♥-X, it has merit but is really a specific instance of maximal overcall, specific as to level of intervention rather than as to Responder's first action. I also think it has merit in the context of a two-suit negative. Thus, for example, after 1♣-1♦-X-3♦, 1♣-2♦-X-3♦, or 1♦-2♣-X-3♣, a double by Opener operates as a way to show some fit (unspecified yet) with a different range than naming the fit. However, this also is alternatively an expansion of the maximal overcall double, perhaps. Thanks for the info as I had not seen it before :)