http://www.quirksmode.org/bugreports/archives/safari/index.html "Explorer Mac and Safari also trigger the onload event when you use an internal anchor to jump to. The jump is executed time and again. (ppknote: This bug is closely related to Setting location.hash to the same value twice causes reload, but it's not quite the same.) Test page http://www.s-seven.net/safari_bug.html Workaround is not included Reported by: Benjamin Eric Morin."
The patch for Bug 6309 may have also fixed this. Needs testing.
The bug page itself notes that this was fixed with r12598, which was the fix for Bug 7058. *** This bug has been marked as a duplicate of 7058 ***