I'm not sure if anyone ever noticed, but in snow leopard in Terminal on top corner of your scrolling there is an icon also can be used through apple key + D
How do i use both windows independent from each other? Otherwise what I see I get a mirror
You're misinterpreting the feature. It's not meant for two separate terminals. It's intended to allow a user to see two different view points in the same terminal. For instance, if you have 3000 files in a directory, and you perform an ls command, that output is going to be very long.
If you use the split pane, you can scroll through that long output without having to flip back and forth, possibly losing your place along the way.
If you want two terminals, use tabs, or separate windows.
I think what you are looking for is the 'screen' command. Take a look at its man page. It basically allows you to have several virtual "screens" within one terminal window (without tabs or multiple windows).
Quick start: execute command 'screen' in your terminal, press return, then press CTRL+A CTRL+C to open a new screen, then press CTRL+A CTRL+A to switch between the 2 screens you just created.
Take a look at this podcast for a nice explanation (the stuff about 'screen' is at 3:10 in the video): http://movies.apple.com/datapub/us/podcasts/leopardserverquicktours/quicktours-31-terminal_tips.m4v
The split pane function does exactly what it does in a text editor: splits your current terminal window in half and lets you scroll each half separately.
It's extremely useful when you want to look at the output of an earlier command while continuing to interact with the command line. Much easier than scrolling up and down between two sections!
I think the split terminal acts more like split command interface. So once you run a editor command in one of the pane, the views are now isolated. You cannot independently control each pane. If you are in command line mode the mirror works to split the command line interface.
It is either intentional or probably a bug - there have been a bug report filed on this.
Anyway, the Split Pane function is pretty much useless at this stage for Terminal addicts - it is just a mirror function, and if it is intentional, no one knows what need this particular function fulfills.
Pray it gets fixed in 10.6.2. :)
Meanwhile, if you want to work with two Terminals independently, you can use either a new Terminal tab, or a new Terminal windows altogether.