OpenCL system, device type

In specification
A device is defiend as below,

Device: A device is a collection of compute units. A command-queue is used to queue
commands to a device. Examples of commands include executing kernels, or reading and writing memory objects. OpenCL devices typically correspond to a GPU, a multi-core CPU, and other processors such as DSPs and the Cell/B.E. processor.

Does this mean a platform cannot have more than one device of type CPU which is being host CPU/multicore CPU?
Or would it be implementation defined?

The platform can have more than one device of type CPU. This totally depends on the OpenCL implementation as to how they want to expose the multi-core CPU to the user. For example, a 8-core CPU could be exposed as 1 CL device with 8 compute-units or 2 CL devices with 4 compute units and so on.

Have a look at “device fission” in AMD’s OpenCL implementation, e.g. here