I know this is an old post. The topic itself however is much much older.
I remember that back in 2012/2013 I furiously posted this feature request, because, for the life of me, I could not understand how something simple like this has been overlooked. Now it's August 2019, and lastpass is still idiotically relying on "equivalent domains".
Do yourself a solid and migrate to anything else than lastpass. I discovered that enpass is a nice choice and free, for mac/windows/linux/ios/android. For mac, you can also use the standalone 1password, which a lot more polished and functional than lastpass will ever be.
Feel free to just not hold your breath on the support for multiple URLs feature, because you may hold for more than a decade by now.