I think I see where you're going with the question. You can NOT count a 50-nm x-country twice -- you're still 60 hours shy. If you flew 49 nm from A to B for 1 hour, that's 1 hour towards the XC req. If you flew 51 nm from A to B for 1 hour, that's 1 hour towards the XC req, not 2. Forget about the 50 nm rule and count the hours all your flights where you went from A to B.
There is one caveat: Ethically and perhaps legally speaking, you should only count the time it took you to get there. If you flew 20 nm to another airport and then spent 2 hours doing touch-and-goes with a student, you should only log the .4 or .5 hours it took to get there, not 2.4 or 2.5. Of course, how you fill out your logbook is your business. Just be prepared to back it up if an employer asks.