Can I sign up for more than one account Google Adsense?

No. Publishers are not permitted to maintain multiple AdSense accounts under the same payee name.
However, we've provided some guidance below that may help you if you're trying to submit multiple applications. Please identify which common reason best describes your situation, then follow the instructions below.
1) I need to change the login of my existing account

If you have access to your existing AdSense account, please log in and select the My Account tab. Under the Login Information section, please check to see whether the phrase "edit in Google Accounts" appears to the right:

• If the phrase appears, please click the link and update your login in Google Accounts. *Note: Gmail addresses cannot be changed.
• If the phrase does not appear, simply follow these instructions to update your login.

2) I can't access my existing account

• If you've forgotten your login:
  1. First, search all of your email inboxes to find the original approval mail we sent you and determine your AdSense login
  2. If you still can't find the approval email, please fill out this form to have your approval mail re-sent to your original email address.
• If you've forgotten your password:
  1. Visit Google Accounts to have your password re-sent to you.
  2. On the page above, if you receive the error message "There are no accounts in our system with the E-mail address ..." then please use this form to reset your password instead.
• If you've forgotten both the login and password for your existing account:
  • Please submit a new application. After we disapprove your new application, we'll work with you by email to help you close the original account and activate the new one. If you choose to follow this path, please be aware that you'll have to replace the ad code on your sites with your new ad code, and that any unpaid earnings of less than $10 will not be issued. Please understand that we take these precautions to protect publisher account security.
• If none of the above login access issues applies to you, then:
  • Make sure you are using both the correct login and the correct password for your AdSense account, rather than your Google Account. Otherwise, you might see an error message reading "Username and password do not match."
  • If all else fails, contact our support team.

3) I need to add more sites to my existing account

• You can use your existing account to do so. Please see our entry on adding more sites.

4) I need a separate account for my business

• In this case, you may submit a new application. Please make sure that the account type (individual or business) and payee name are different from your original application, and ensure that you can accept payments to that payee.

5) I need more reporting channels

• The maximum number of channels we currently offer is 200. Unfortunately, we can't accommodate requests for more channels at this time, though we do hope to increase the number of available channels in the future.