Trying to test new form added to Adobe Muse.

This is the response after completing form in Muse live:

"Sorry! Only one entry is allowed. Multiple submissions are disabled for this form."

How to fix?

It appears that your form has Unique Submissions enabled to "Check cookies and IP". This means once there is a submission from a specific IP address, no further submissions can be made from the same IP. This allows you to limit the submissions to only one submission per IP. 

To disable the Unique Submissions option and allow multiple submissions on the same IP, simply open your Preferences.

Then click Advanced tab and set Unique Submissions to No Check.

You can also check out this guide for more info on unique submissions: How to Set Unique Submissions on a Form

Please let us know if you need further assistance.
Regards.