There are many users who want to use two alias's on IRC Channels so this can be done using these following commands:
/msg NickServ help
This will show you number of functions that can be performed by using /msg NickServ command.
Now, /msg NickServ group primary_nick password
Here, primary_nick is the alias which you want to link with your new alias.
And password is of primary_nick.
And it's done, now you can use two nick's/alias's.