If you don't need to format the data in any particular way, you can loop through the first array, then use str() to convert the data to a String array, then combine the data, then save it with saveStrings().

How would I combine the data? Could you give me an example..?

Loop through it, then concatenate it to a new array...

NOTE: An often confusing subject; a two-dimensional array is just an array of arrays, so it can be looped through like a normal array.

Like this (untested...):

1. String[][] inputArrays;
2. String[] outputArray;
   
3. 
   
4. for(int i = 0; i < inputArrays.length; i ++) {
5.   outputArray = concat(outputArray, inputArrays[i]);
   
6. }