A man has created two wills. Which will be treated as final. The First one or Second one?

The first thing every will provides for is the cancellation of all prior wills.  The second one will supecede the first.  If for some reason the second will did not explicitly cancel the first, there could be a problem.  The second one will supercede the first, but possibly only as to those provisions which directly contradict the first.  For example, let's say John's first will provides that he leaves his house to Mary, while the second will provides that the house is left to Steve.  Steve will get John's house.  However, let's say that the first will says I leave $5,000 to Mary, with no mention of Steve.  The second will leaves $5,000 to Steve, with no mention of Mary.  If the second will has not expressly cancelled all prior wills, is is possible that it will be treated as merely modifying, not cancelling, the first will.  In that case, both Mary and Steve will get $5,000.