Are you trying to get both flashes off camera? Or have one speedlite on-camera?
From what I understand (and it's not much, so you may want to read
the Rob Galbraith review of the units) if you want to keep a speedlite on-camera as a master or manual light, you just need the MiniTT1 transmitter on-camera (and you can mount a speedlite onto it) and a FlexTT5 transceiver for the off-camera flash.
If you want to use the MiniTT1 transmittter as your master, then you'd need two FlexTT5s transceivers to use both flashes off camera.