if not more than

[Joe]

I saw a sentencel like this:
The setting for the premiere promised to be as grand, if not more, than the film itself.

I don't think the underlined part is correct. I think it should be "to be as grand, if not more than, as the film itself". Do you agree with me? Thanks.

original might be ok
yours is definitely wrong. i understand what you're trying to do with the agreement/parallelism, but no

i would say 'if not more SO,'