Yes. God understands many particular types of things (and these are many ideas) because the divine essence is not called an idea insofar as it is that essence, but only insofar as it is the likeness or type of this or that thing.
Hence ideas are said to be many, inasmuch as many types are understood through the self-same essence.
Relations, whereby ideas are multiplied, are caused not by the things themselves, but by the divine intellect comparing its own essence with these things.
Relations multiplying ideas do not exist in created things, but in God. Yet they are not real relations, such as those whereby the Persons are distinguished, but relations understood by God.
It is not repugnant to the simplicity of the divine mind that it understand many things; though it would be repugnant to its simplicity were His understanding to be formed by a plurality of images.
Hence many ideas exist in the divine mind, as things understood by it.