Parallel space is a very nifty useful app if you wish to have two accounts of apps like Whatsapp, Facebook, Instagram, Clash of Clans and many such apps and games on the same phone.
This app is seamless in swtching between accounts and is very fast in doing so.
Only drawbacks are notifications and some crashes.
Also the app is less than 3MB so easily can be downloaded.
However more the apps cloned more it takes space on your phone.
I have cloned Whatsapp, Instagram and Facebook and it takes around 200 MB of my storage space.
Other than that a very useful and a must have handy app.