I'm working in a videogame with a friend but I want to know if we can work at the same time with differents versions of the project in local and then merge the maps in a unique version.
The best solution would be to use Git to handle conflicts correctly but it's not really friendly user.
Another solution is to use Cloud. If you want to separetely work on different maps, here is an example of what you could do: copy the project with a created map you want to work on, work on it separately, when you are done with it you can check the ID of the map (right click on it, edit map properties, ID is just on the right of the name), then you can find the map folder in YourProject/resources/app/Content/Datas/Maps according to the ID. You just have to copy this folder and overwrite to the original project.
/!\ The original project should already have the map created before working on it separetely. If you change tileset, pictures, etc it won't be stored in your map folder, but in datas files located in YourProject/resources/app/Content/Datas (.json files).