How is the second session started. When xinit -- :1 runs, it will use the next available vt number which normally is in vt08, hence ctrl+alt+F8.
It is possible to automatically start to x windows servers and assign the vt used, for example with the gdm config file:
It is not normal to be running two instances of x windows at the same time. But if you are, you need to determine which vt is used. If it is vt09 then ctr-altl-f9 would be used instead.