how to randomly add data from a directory to data present in another directory

I have two directory named as dir1 and dir2.

Both the directories contain time-series data.

In both the directories time series are saved in text files with two columns time and amplitude.

All the time series in both the directories are of same length and additionally the time column is same for all the time-series data only there is variation in amplitude.

Now I just want to iterate through the timeseries of dir2 so that randomly any timeseries from dir2 will be added to a timeseries present in dir1 and finally I want to see all the timeseries in dir1 is successfully added with randomly picked data present in dir2and the results should be saved inresults directory`. Hope i will get some solution.

what i exactly need is given in link please have a look https://i.fluffy.cc/11Tmd3l7ZtS6ClVJRRNb8mkhD3hgd99m.html

my data looks like as below

time     amplitude
10.0       5.6
11.0       5.8
12.0      -2.4
13.0       6.8
14.0      -2.9
15.0       2.4