Text file with time stamp

[honigtau]

Hi I have two directories with text files which I have to merge.
Each text file has a time stamp per line like this:

dirb\File1.txt
[2009/12/08 18:11] text text
[2009/12/08 19:39] text b

dira\File1.txt
[2009/12/08 18:15] a text
[2009/12/08 22:22] b text

At the end I would like to have one file:

[2009/12/08 18:11] text text
[2009/12/08 18:15] text1 text2
[2009/12/08 19:39] text b
[2009/12/08 22:22] b text

I have no idea how to manage this with BC.