Multiple ssh keys for github through ssh config

I am having two github accounts for my projects.At first i used to work one git account from my desktop and other through my laptop.Now i want to access both the accounts from a single linux user account.

First i was trying to generate the ssh keys for my first github account with help of this article.Now i can able to use to access github.Next i was about to generate ssh key for my another github account, while creating the ssh key, it prompts for over writing the existing key.So here comes the problem.If i overwrite, then my ssh key for the first github account will get lost.So i won't be able to acces the account.

And then i stumbled across this article that makes me to define all my aliases for machine names, per-host access controls, and more

Here is my $Home/.ssh/config to customize SSH for a specific host:

Host github.com
HostName github.com
IdentityFile ~/.ssh/id_user_client
User jude

Host github.com
HostName github.com
IdentityFile ~/.ssh/id_user_gen
User genlinux


Now i can able to access my two different github accounts by customizing the config file in $HOME/.ssh