I have built shared tees a few times.
At The Legends (Heathland), the back tee for #9 is shared with the middle tee for #11, the the middle tee for #9 with the back tee for #11. They're staggered off to the side so it works fine.
At Lost Dunes, the tees for #2 and #5 are up on the same ridge and back to back, so you can move back further if you want.
At Sebonack, the tees for #17 and #11 are sort of shared ... if you play #11 from the back tee of #17 it's well over 500 yards.