Module Names - Hyphen Converted to Underscore

[AJM <ajm@transtec.demon.co.uk>]

I have compiled stock (kernel.org) 2.6.3 and 2.6.9 kernels which exhibit 
the following unusual behaviour on module loading: If the kernel module 
has a hyphen in its name, then this appears to be translated into an 
underscore by the kernel, such that, for example after "insmod 3w-xxxx", 
lsmod shows "3w_xxxx", "rmmod 3w-xxxx" fails but "rmmod 3w_xxxx" succeeds.

The distribution I am compiling the kernels under is Mandrake 10.0, and 
if I compile the 2.6.3-4mdk kernel source supplied with the distribution 
  then this problem does not arise.

A Google search reveals a number of similar problems, but with no 
explanation other than possible typing errors.

Any suggestions as to why this is happening?

Thanks in advance,

Jonathan.