I am a bit unclear on what you mean by "merge" you email. It sounds like what you want is to synchronize your mail. Are you using the same account and logon info? How is your email hosted? What version of Outlook are you using?

Most email systems allow you to leave a copy of each email on the server. Outlook's default is to NOT do this. If you leave a copy on the server you will be able to access all mails from any machine you use to log in to your account. That will be in the Tools>Internet Options>Connection options, if I remember rightly.

I used Dogpile.com to search the term "synchronize outlook" and came up with a bunch of stuff that may or may not be helpful, but many of the results were for third-party software that performs this specific duty. Some solutions