STAAD.Pro cannot check double I profiles as per Eurocode. The only design code in STAAD.Pro that I am aware of, which handles the design of double I profiles, is the Indian steel code IS-800:1984. ( CODE INDIAN )
Double I profiles can be modeled using the Double Profile option, when defining sections from within the Section Profile table as shown next
Star angles can be defined using the Star angle option, as shown next
Design of star angles is not supported for all codes. I know that design for star angles is implemented in the Indian IS-800: 2007 LSD code for sure (CODE IS800 LSD )