I have filled the ssc cet exam application form but when i submitted it instead of print it came error.And now if I try it again then it is coming already registered.
The problem you have faced is due to the server problems. I would say that you should log in the account and check there can be options for downloading the receipt again. If you can't find it or if this problem didn't get resolved in 48 hours of time then I would recommend you to contact the officials and discuss your problem. They can help you out.
You can visit the link below and can contact using the phone number provided:
http://mahahsscboard.org/contact.htm
I hope this helps.