Hey, I am not sure I get you right.
When you, as an author of map called MapA, make changes to this map, then you have a choice, you can update this map, or you can publish this map as new one by pressing publish new button.
When you wish to change or modify someone else's map you only can publish it as new, because only author can update it.

I'm trying to address to the people updating their own works, you can see several duplicates/updates made by the same person.

Try this: https://steamhost.cn/steamcommunity_com/workshop/browse/?appid=356570&browsesort=mostrecent&section=readytouseitems

I think I played 4 egg parties which looked all the same. Several mountain parties.

I think you should write that to each duplicate map's comments area. Creators may not read that here. But they get notified about comments.
Don't know whether the dev of a game can do anything about the Steam system.

There was a duplicate labyrinth party too but one was so bugged that it couldn't get finished, wrote that on that map board and apparently the creator didn't know how to delete a map. Took him several days to figure it out. It's luckily gone now.

Taking your suggestion, hopefully people won't flak me.