Yes in Illinois there is no possession limit. You can fish different lakes in the same day. Although there are laws about not taking fish from one lake to another and by law you are supposed to drain your live well on the ramp where you are before you leave. stupid law and does not get enforced due to the fact of the tournaments. I would not recommend having fish in your live well from a different lake, better off to take them home or clean them first.
CX.