Question about unique drops

Back in the days before Resurrected, there was a rule: the same unique item can't drop in a single game session. While true, that rule was misleading to think that you could force a SoJ dropping by dropping a Nagel and a Manald in a game, but I know that's false, if the same unique would drop and it already dropped, it would roll as a fail unique.

But what about classic D2? I never played classic, I read that if you keep the unique, that unique would never drop again, can this be used to force a SoJ, or would it be just another failed unique?