I saw three examples of this in one day! Two in the New York Times! Example with discussion below:
Name your second-favorite airport- or airplane-based movie.
“Die Hard 2” was certainly was an influence.
—from interview with T. J. Fixman, writer of Netflix movie Carry On
Just a general discussion because I don’t know how to rate errors like this, annoying to read as they are. Your eye might have skipped over it. In the author’s response, the passive verb was gets repeated before and after the adverb certainly. Presumably when first typed, the writer of this sentence wasn’t certain whether to split the verb from its descriptive object influence (called a subjective complement to be exact). Did this occur because the author thought the editor would pick the ‘right’ one? Technically both are correct, but I could make an argument for “certainly was”. Is the author self-editing, and planned to come back to this? Or, as I fear most likely, did the author have a brain-fart, being unable to carry the sentence construct mentally for only three words?
Twice in one session of reading, New York Times? When I saw a third one on a sports blog, I couldn’t believe it, but at least it’s written by dedicated amateurs more interested in sports than writing. I can’t rate it because it’s egregiously wrong, yet quite possibly represents a case of just typing too quickly and hitting ‘Send’.
all the voices in my head 
For the above example I would suggest a 3rd possibility. The way I read it, I’m assuming it was taken from a live interview and it ‘appears’ to be a direct quote of an answer to the interviewer’s question.
If so, perhaps the speaker stumbled in their answer and the recording transcription was not properly edited to include the implied pause used by the speaker as they corrected themself. (e.g. “Die Hard 2” was, certainly was an influence.)
I suggest this because just this past week I was introduced to an ai recorder / live transcribing app. My cousin used this app to record me as I talked about our family history. As I understand it, the app is not perfect so the transcription must still be reviewed and edited for punctuation and homonyms, and so forth.
It could be a useful tool for quick interviews, but it still requires proper editing or else we risk publishing the type of readers horror which you have pointed out above.
(personal note: I’m hesitant to make this long comment, since I’m almost certain that I have committed a few errors myself 😁)
Sorry to put such fear in your heart. That’s a good supposition, but merely makes it an error of a different sort. A 4th possibility is the interviewee messed it up, because sometimes these so-called interviews occur in email.
I was a journalist for years and I’d say this is an editing error. It was probably transcribed sloppily by the reporter thinking it didn’t really have much of an effect on the story and “it would be fixed in editing.” The editor probably mistook it as an exact quote and left it. That’s my guess.
Maybe. I might be overly cynical. I still think it’s possible there *was* no editor.