I am not sure, if this is the easiest way, but I do this the following way: It looks like you can only copy and paste midi within the same track, but drag to other tracks. So I create a copy of the midi in the same track, then drag it to a copy of the track and change the instrument, like this:
- In the track view double tap the track head of the virtual piano with the lucky take, till you see the edit options, select "dulicate". This will create a copy of your piano track, but without the midi.
- Now double tap the midi region of the lucky take and select "copy". Tehn lelect an empty place on your track, again double tap, and paste the copy there.
- Now drag the copy to your second piano track.
- Tap the instrument in the track head and select a different instrument.
It is limited, how you can move regions between tracks. Basically, you can move between tracks with the same touch instrument. See the help: http://help.apple.com/garageband/ipad/2.0/index.html#chsec12c15d
Move a region
- Drag the region left or right to move it forward or back in time. Align the left edge of the region with the bar or beat on the ruler where you want it to start playing.
- Drag the region up or down to move it to another track with the same Touch Instrument. You can also drag regions between Keyboard and Sampler tracks, and between Audio Recorder and Guitar Amp tracks. Smart Drums regions cannot be dragged to another Smart Drums track.
If you move a region so that it overlaps another region, the overlapped part of the “covered” region is deleted.
Paste a region
You can paste a region you have copied, or paste an audio file from an app that supports copying audio to the clipboard. GarageBand supports 44.1 kHz sample rate, 16-bit depth uncompressed audio files.
You can paste copied regions to another track with the same Touch Instrument. You can also paste regions between Keyboard and Sampler tracks, and between Audio Recorder and Guitar Amp tracks. Smart Drums regions cannot be pasted to another Smart Drums track. Audio files copied from another app can be pasted to Audio Recorder or Guitar Amp tracks.
- Move the playhead to the point where you want the region to start.
- Tap the header of the track where you want to paste the region to select the track.
- Tap the track where you want to paste the region, then tap Paste.You can also tap an empty area of Tracks view, then tap Paste. In this case the region is pasted into the currently selected track.