apache2 - Compiling PHP from source (an old version) will delete or corrupt my current PHP7? What is the proper way to install both + switch between them?

I have PHP 7.1 on my Ubuntu machine.

I need to work on a project that uses php5 5.3.3-7+squeeze17 (yes... a 10 year old code).

I have found the source of this package: https://launchpad.net/debian/+source/php5/5.3.3-7+squeeze17

If I install php5_5.3.3.orig.tar.gz following using any of these methods:

Will this corrupt my current PHP 7.1 and prevent it from working? (- might this change the settings via Apache2 on install make?)

What is the proper way to install this version, so I will be able to switch between both versions?