Hi Igor,
the ABAP application sever does not support this as part of the standard. Two me, what you are askining for sounds like two factor authentication. If you want to achieve something like this, you need some SSO product like SAP Single Sing-On. However even there, I'm not sure, whether a combination of X509/SAML and user/pass will be supported. Could you please tell something about the use case?
Kind regards,
Patrick