If the 63 miler was a fair amount more than you are used to it might seem prudent to keep today down to a relaxed 30 or so like RickOCRR says. But, in general, as long as you are not sprinting or otherwise maxing out your muscles shouldn't it be fine to do multiple 50/60 mile rides? Lots of people ride cross country averaging 70 miles or more per day at a moderate pace.