这两句话的重点，可能不一样。The two sentences are different in this way:
They're both about activities, but
第一句: connotation : 昨天下课了，有点闲, 所以出去溜达溜达，散步去了。
the first sentence tells us indirectly the speaker got some time after the class, so he went for a walk.
the second sentence tells us indirectly that right after the class, he went for a walk. There's no delay between the two.
At least, that's what I thought.