No there will only be one birth certificate. Look at the ref numbers, are they the same?
It’s perfectly normal. My great nephew and his two sisters are on the register 3 times. His parents aren’t married. He is indexed once as John Brown * ( mother’s name) once as John Smith (father’s name) and once as John Smith-Brown ( the name he uses) His birth certificate is in the name of John Smith- Brown. There is only one birth certificate.
* not real name.