Which is correct word "Log in" or "Login" [duplicate]

"Login in" and "login" are just like "back up" and "backup", and many other similar expressions.

The double word form is a verb, while the single word form is a noun.

Try parsing the verb or pluralizing the noun. There's only one way it sounds right:

• "He logs in every day", not "He logins every day".
• "There were several logins yesterday", not "There were several logs in yesterday".

or:

• "He backs up the data", not "He backups the data".
• "The backups are stored elsewhere", not "The backs up are stored elsewhere".

In your example, you could say "The employee logs in upon arrival and logs out upon leaving" and "The logins and logouts of all the employees are recorded in this book".