It quite most common when you use different computers as your work place and office, or you may have a combination of laptop and desktop on which you work on.
Tarylynn is a free multiple folder syncing tool which lets you sync your laptop and desktop together or any two other computers which could be on the network. It comes with an integrated FTP client, which means you can even work with remote computers.
This program analyzes and compares the content of the selected folders and lets you decide on the run time whether copy data, delete it, from right to left pane or vice versa.