im obviously new so how am i to know that its already been answered? i also note that your answer isnt complete. is the lack of rom battery an issue exclusive to mac emulation or to genesis emulation as a whole i.e. can user data be saved when playing a rom of the game in windows?
also, i have downloaded another mac emulator called generator and tested the game on that. it exhibits almost, but not quite, exactly the same behaviour. the only difference is that when returning to the main menu having won the first play off game, the team names listed are the correct team names however it still shows two ducks logos at the top of the screen and if you go ahead to play the game it is ducks v ducks.
as far as i can tell both genesis plus and generator are mac ports of the windows emulator gens. seems weird that two separate ports of the same emulator would exhibit the same issues. there is another mac emulator called dgen but i havent been able to find a working download after a brief search so idk if the same issue is present in that. it would be interesting to find out if it is.