How is this possible?

[85]

I'm not sure this is the proper section since i'm not directly requesting anything and is not properly called "hacking" but I was wondering how was possible there was tons of APK which are IDENTICAL each other just the name (and the owner) changes.

I was looking at some of those "Whatsapp Online Monitor" apk and there are many like: WhatsMonitor4, Wnotify, WhatsD0g ecc which are made in the exact same way but just the name changes. 
How is that possible? Is there a way for me to do the same? Because most of these apps give you 24h free but then they ask you to pay and i'd like to use this on my sons without rly paying :o

[18]

you can open the apk and change it and reupload it but mostly you must download it from other store not directly from google play store . yeah this way is possible