I am proofreading a professional, technical text written by someone else. In the text, I encountered, "But, the reality is *is* a..." My intuition says that this should be rewritten as, "But, the reality is *that* a..." because it looks like a "double is" or a "[double copula](http://en.wikipedia.org/wiki/Double_copula)"

However, I can't tell for sure if this is a legitimate use of two successive copulae. Does, "But, the reality is..." qualify as a dependent clause? It seems to me that "But,..." does not make the subject dependent. Am I right? Am I wrong?

The sentence with a little more context:
"But, the reality is is a company like *Spacely Sprockets* cannot continue to *do old fashioned things*..."

(We have already had a discussion about beginning sentences with "but" in professional writing. It appears that the consensus is that it is both appropriate and acceptable here.)

I would like to see a way to clearly identify this statement as something that ought to be changed in the document. Grammar dissection, linking to authoritative works and explanations of grammar mechanics will all help me answer this question. Simple answers like, "it's wrong," don't help me be a better proofreader or editor. I already know it is wrong, but I don't know *why* it is wrong.