You can use a define for that. Im not sure if its possible on a different way, never needed such a feature.
Code:
#define test test2
int test(int i)
{
return i * 2;
}
#undef test
int test(int i)
{
return i * 4;
}
int main()
{
printf("test: %i\n", test(1));
return 0;
}