Won 9/03/2021 Truck Racer - FF72M-LXTBE-KFN3M
Won 15/03/2021 Grotesque Tactics: Evil Heroes Comp - DCLQN-Z3MGP-K9R59
Won 17/03/2021 Disciples II: Rise of the Elves Comp AVIIR-3LQTP-AGZHM
Won 23/03/2021 Crash Time 2 Retail E3MJQ-Q3LPT-G5P2X
Here's another speculation:
Tropico 3 Reloaded - looks like all reported dupes begin with "B", while a key beginning with "6" worked for me. Can anyone else share what their working Tropico 3 key begin with?