It could result from pure coincidence; could result from one or both writers simply recalling something they had heard, not as something they had heard, but just as a way of conveying three closely related thoughts. It happens all the time, that people use phrases they have heard, without consciously seeking to copy phrases they have heard.
The way to handle this, as I have pointed out in #145 is head on. Let Melania introduce a video of her very effective speech, by explaining the controversy, and asking the viewers to judge the effort for themselves. Putting the whole thing in context completely destroys the idea os some sinister purpose--particularly when it is the speaker, herself, who invites the judgement. She has the natural ability to make this very, very effective.
This could be as effective as Nixon's "Little Dog" speech (about "Checkers." It is opportunity. Properly handled, she could reach a huge audience--a classic opportunity to sell Donald Trump to many now scoffing. (That is because many non-Trump would tune in to see what this whole flap was about!)
If it is so common, find me the example from someone else. Go ahead. I tried and can’t find it.