Why there is only one form allowed per computer?

According to the other thread you opened: https://www.jotform.com/answers/1093295. You're asking why your client cannot submit multiple entries. 

You need to disable the Unique Submission by choosing the No Check in the drop down menu. This will let your client submit as many times as they want in one computer. Here's how to disable it:

1. Open your form and go to the Settings section page. Select the Form Settings tab and click the Show More Options button.

2. Under the Unique Submissions, select the No Check option in the drop down menu. 

Here's a guide: How-to-Set-Unique-Submissions-on-a-Form

Hope that helps. If you have questions, please contact us again. Thank you.