Hope you are doing well and sorry for the trouble. As described, you have removed the signature fields and added them in the sending process and the every single time when you send, it still adds another automatically for signatures.
It is the design behavior of the application. If the application doesn't detect any signature fields added in the PDF file while sending for signature, it automatically adds them to the document. You may stop adding the fields in the sending process as they will be added by default.