Remember that in TOS' time, nobody really knew what class the Enterprise
was, whether it was the first ship of its kind, or pretty much anything else about it. So the use of the number 1017 for the Constellation
was not seen as a big deal.
And in the end, is there any actual proof, even in the remastered version, that the Constellation
is the same class as the Enterprise
? We now know that the Enterprise
-class, but there's no proof that the Constellation
was of that class. It could be a different one entirely. We've only seen the Constellation
as a destroyed hulk. We have no idea what it looked like 'fully formed', as it were.