Old ManicTime database timeline (ManicTime.sdf)
Although you can use ManicTime server to share data between clients, it can be an overkill to set it up for some simple home scenarios. If you just want to combine the data from two databases, lets say create a timehseet from two locations, you can use the new ManicTime database plugin. It will load timelines from another database.
Open Timelines editor
Click on Add timeline, then select ManicTime Database.
Once you enter the location of the database, click Test connection and choose the timelines you would like to import. For timesheet you only need to import the Tag timeline.
If you want to use a newer backup you can just close ManicTime, copy new backup over the old one and start it again. MT will then use the new database and load the new data.