Hi,
0 (FPC 0) Prsnt XXXXXXXXXX ex4550-32f 255 Master* Y VC 1 vcp-255/0/0 1 (FPC 1) PrsntXXXXXXXXXX ex4550-32f 255 Backup Y VC 0 vcp-255/0/0
All interfaces starting with xe-0/*/* are from FPC 0, i.e member0 and interfaces xe-1/*/* are from FPC1 / member1.
"On an EX3300 Virtual Chassis, an EX4200 Virtual Chassis, an EX4300 Virtual Chassis, an EX4500 Virtual Chassis, an EX4550 Virtual Chassis, or a mixed Virtual Chassis, the FPC number indicates the member ID of the switch in the Virtual Chassis."
Cheers,
Ashvin