You probably have lots of overlapping queries. If your application generates 20 simultaneous queries that all start at 00:00:00 and then all finish at 00:00:02 the elapsed time would be 2 seconds, but the sum of all durations would be 40 seconds.

It is also possible that you have some queries that take a very long time to complete - possibly because of locking.

Note that the number of overlapping queries has nothing to do with the number of CPU:s in the machine. Even with a single CPU server it is possible for the clients to generate lots of overlapping queries - especially if there are multiple clients involved.

So, in short: It is perfectly normal for the sum of durations to be longer than the elapsed time.

/SG