As the above stated, some regs use LH threads and others use RH threads. If they're identical regs they should have the same threading directions. Keep in mind that he high pressure ports may have different threading than the low pressure ports. If the two regs have opposite threading directions, they make pipe that has both RH and LH so you can join them.
I've seen the pipes at Midwest Supplies, off the top of my head. I did the exact thing you're doing last month. When I was asking about it people mentioned that you can't use just any pipe since it's the high pressure ports you're joining. Do you have a desired vendor? My LHBS hooked me up with both the new reg and pipe.