When there are more than one person in one project, the save will definitely overwrite the last save. However, it always raises a problem that the other just keeps their session open and do not refresh the page, and the new changes will never be shown to them. When they press save even if nothing modified (just as their habit), the new changes were overwritten and they will work on the old version without noticing the new changes. As the person reloads the page or keeps working on the same session, he either get another totally different variation or keeps working on his own variation. This will make the entire job quite hard and inconvenient even if the team keeps frequent communication. Therefore, I would like to request a new feature: when the other person presses save, the software will detect whether there is a newer version in the file history than the version that the saved session is based on. If there is a newer one, a warning will pop-up before confirming the overwrite.