I don't consider using the same block in more than one quilt a repeat of the quilt pattern. Log Cabin, for example, isn't a quilt pattern, it's a block pattern. You could make nothing but log cabin blocks your entire quilting life and never put them together into the same arrangement (quilt pattern) more than once. Same for Drunkard's Path and a myriad of other blocks. That said, I've never duplicated a quilt pattern, mine or anyone else's.