[LAU] recording again over a normal track on Ardour

[Federico Bruni]

Hi all

I've just recorded two tracks on Ardour and I have recorded again two 
parts of a (normal) track. I've not created a new track, I recorded it 
over the first recording.
I don't know what's the best way to do this...

Anyway, it worked fine except for few seconds at the beginning, where I 
can hear both recordings together. The area is highlighted in yellow and 
has two lines crossing.
How can I remove the old recording and keep only the last one?
And why it happened?

Thanks in advance
-- 
Federico