sounds about right.
You obviously have the main engine/transmission ECU which is the one most people mean when they just state ECU but almost every other system has its own ECU. e.g. there is one for each door windows and power locks), tyre pressure warning ecu , reversing sensor ecu, skid control ecu, steering wheel tilt/reach ecu, shift lock control ecu, cooling fan ecu, power management control ecu etc. etc.