For two people to work on a game at the same time, you would not only need two different monitors, but two completely different computers. Maybe that's what you're asking?
None of the engines are designed for multi-user. You can each develop different parts of the game and then combine them together into a single project as you go, but it needs careful planning and organization, to ensure one person doesn't overwrite what the other person has done. You could put the project on dropbox and both develop from there, however if you both open the project at the same time to work on it, and one of you is doing database stuff and the other is doing maps, when the person doing maps saves, they will clear what the databaser has set up.
It is much easier if you both work on it at different times - that will mean what the first person does gets saved before the second person starts work, so when the second person starts, they get everything the first person has done.
If you absolutely must work on it at the same time, I suggest one of you works with the engine and the other does non-engine stuff - using a spreadsheet to figure out stats, build tilesets and gather resources, etc.
