I needs to file extension for 1065 partnership   before 3/15/2024 . I got  extension rejection code F7004-011-03
"Message : Taxpayer EIN in the return header must not be the same as an EIN of a previously accepted electronic return for the return type and tax period and Type of Return Code indicated for the tax return type ".  Searching the code should be already efiled extension.  I double checked EIN, officer tax ID and name and address correct. I already mailed form 7004 for client. Can I file original return 1065 if someone else (former tax preparer or client efiled extension? I asked the client and they consisted "NO". I am trying to call IRS xxx.xxx.xxxx but it is nightmare to wait for 
Any advise or experience, please help. Thank you