History senstive merging?

[Neal Becker]

Giorgos Keramidas wrote:

> On Thu, 11 Dec 2008 13:33:21 -0500, Neal Becker <ndbecker2 at gmail.com>
> wrote:
>> What do you recommend for history sensitive merging?
>>
>> I have a file A, which I copied and modified into B.  Now I want to
>> take the updates to A and apply them to B.  What 3-way diff tool is
>> good for this?
> 
> If you used "hg copy A B" to perform the copy this will happen
> automatically with _any_ merge tool.

Is hg copy appropriate for the case where A and B are intended to really be different files?  In my case, A & B are 2 python scripts that I want to always be different - yet they have common ancestry and features.