Replacing english.php too many times

My question should be fast and simple.

If I insert a contribution such as ebay exporter and replace (for example) //catalog/includes/languages/english.php.

and later on I install another contrib such as fed ex ship and it asked me to replace the same file, did I loose the code that I need for the first contrib? If so, how do I fix this.

The contribs that I mentioned in this question might not replace that file or even exist. That is not the question. My question is if they did, will they screw up?

If you have two or more mods which modify the same file(s) you will need to edit the file(s) when you install the second mod so you don't lose the changes the first mod made.

I use Compare It! to do this.