Duplicate a Safari tab along with associated browsing history (OS X)
Solution 1:
Not a solution (yet), but fyi you might want to keep an eye on this, if it gets implemented: https://github.com/thiemo/duplicatetabbutton/issues/2
Solution 2:
It's not quite what you want, but you can set the default tab behavior to be open with same page, which will preserve your history.
