Theoretically, no. They will mess with each others' reception/transmission patterns. But if you want to try it...
"In theory, there is no difference between practice and theory. In practice, there is."
Yogi Berra (or an unnamed computer geek, depending on who you ask)
I wouldn't do it, because I have two wingtips. And a half wave nav antenna can be fabbed into the canopy.
Charlie