I don't think it's redundant because teach and learn are different processes.
Learning is often a passive activity, especially at the lower levels of learning, like habituation. I doubt you're familiar with these unless you've had formal training in learning theory. Learning is much, much, much more than what students do in school; its how animals adapt to their environments.
Teaching is always an active process and thus "teaching themselves" isn't made redundant by the use of "learn" in the sentence.