Honorific Progressive Tense

So I was doing my reviews and went over お〜になる and いらっしゃる and on each the answer was in progressive tense however I was wrong on both because on the お〜になる one I put Verb+て+いらっしゃいます and お〜になっています on the other.

Is there any difference between the two?

お召し上がりになっています

読んでいらっしゃいます

(Other than the obvious double keigo)

I don’t the answer and this has bugged me on reviews too. I didn’t know whether this was a missing synonym feature or whether I was wrong.

However, I believe いらっしゃる has a larger variety of honorific scale (such as お読みいらっしゃいます) so I if I had to guess, maybe it has more place in hierarchal situations. I found this source talking about out/in group distinctions when using honorifics. The distinction was between 参ります and いらっしゃいます but I assume similar rule for irregular form or お〜になる