Used the map generator often, I had one seed map that had the trader.
Another seed that had the boss's and left the trophies hanging on the stone alter there saved the hoards of attacks on my own world.
You can use other world seeds legally if you want to use that word and is recomended. Add a new seed for purposes such as gatherings ores.
they appear in the load screen where we can just log in to it and log out go back to our main world. Just give each seed a name you identify with.