So far, to quickly open a new copy of already running program or task I was doing this:
Right-click on program's item in Windows taskbar + select name of that program from the context menu. Turns out there's an even faster way of doing so: Click on program's item while holding Shift button pressed.
Works in Windows 7. May work in other versions (though not tested). You may safely ignore this post, if this is absolutely obvious for you (wasn't that obvious for me).