private function _hasEqualSerialNumber(Certificate $cert): bool
    {
        $sn1 = $this->_tbsCertificate->serialNumber();
        $sn2 = $cert->_tbsCertificate->serialNumber();
        return $sn1 == $sn2;
    }
private function _hasEqualSerialNumber(Certificate $cert): bool
    {
        $sn1 = $this->_tbsCertificate->serialNumber();
        $sn2 = $cert->_tbsCertificate->serialNumber();
        return $sn1 == $sn2;
    }
private function _hasEqualSerialNumber ( Certificate $ cert ) : bool { $ sn1 = $ this -> _tbsCertificate -> serialNumber ( ) ; $ sn2 = $ cert -> _tbsCertificate -> serialNumber ( ) ; return $ sn1 == $ sn2 ; }
Check whether certificate has serial number equal to another.

@param Certificate $cert
@return bool
Check whether certificate has serial number equal to another .