I'm sure that my popup comment window, after a comment had been added, was in the same format as it is before the submit button is clicked.
I just noticed, however, that the refreshed page with the comment added is now the individual entry template, not the popup comment template??

Can I fix this?
You can see this here.
If  you want to add comments to see it, go ahead.  Nobody visits this blog, it's really for me to record my upcoming vacation, and I can go delete them afterwards anyway

Interesting.
Easiest thing to do to fix it is to pull the default template for comments back and re-paste it into the Comment Template in MT.

I think you can get them here under Default templates on the main page.

The problem is that you have this line in your Comments Template listing, in the form area:



Remove it - it is the cause of the redirect to your Individual Archive Page.