It seems that the in Jenkins 'Browse results' duration trend does not calculate suite setup/teardown to whole time. E.g. 'All test suites' first duration value is in my case 12:37:12.503 (whole test set takes 12h 37minutes). If I open Robot report I can see that the whole time is actually 14:47:35.

If I check from 'Browse results' first test suite, it's time is 4:09:17.268, from robot report it is 04:15:05, if I check suite setup it takes 00:05:45.914 and teardown 00:00:01.245. So suite setup and teardown is not calculated by jenkins robot plugin.