General AutoLISP question

Currently I have been setting up functions in a file as follows

;begin file
(defun common_function ()
(..............)
)

(defun c:Option1 ()
(xxxxxxx)
(common_function)
)

(defun c:Option2 ()
(yyyyyyy)
(common_function)
)
; end file

The problem I have run into is that if (common_function) is somehow defined as something else later it causes mayhem. Outside of
making the function local to both c: functions, is there a better way of doing this to address this scenario.
Thanks
Cliff

 

I have accidentally used the same function name again before, but my main concern is sending the code out to others where I have no
control over what is defined. I guess I may start making function names more unique.
Thanks
Cliff