Meaning of verb に verb てる


In an anime I heard this exchage:

> A: 私は商業作家ですもの‌。仕事に対して全力で臨むのはいつの場合でも同じ‌
>
> B: 次回作の小説遅れに遅れてるんです

Given that A is a novel author and is late in delivering her last work, I
think B's phrase means something like "You say that despite being late in
delivering your next work", but I'm not sure how I should understand the
遅れに遅れてる part, and I was unable to find info about it on my grammars or on
grammar sites.

The only thing that comes to mind is taht it gives some sort of emphasis to
the fact that A is late, but I didn't find any confirmation.




The use of [に](https://dictionary.goo.ne.jp/word/%E3%81%AB/#jn-166083) is
emphasis:

> 13 （動詞・形容詞を重ねて）強意を表す。「騒ぎ―騒ぐ」
>
> 「風いたう吹き、海の面 (おもて) ただあし―あしうなるに」〈枕・三〇六〉

I think 形容詞 cannot be used in this construction in the modern usage. See
[this](https://japanese.stackexchange.com/questions/87450/about-phrases-
like-%E5%A3%B2%E3%82%8C%E3%81%AB%E5%A3%B2%E3%82%8C%E3%82%8B?noredirect=1&lq=1)
for some other examples.




The use of [に](https://dictionary.goo.ne.jp/word/%E3%81%AB/#jn-166083) is
emphasis:

> 13 （動詞・形容詞を重ねて）強意を表す。「騒ぎ―騒ぐ」
>
> 「風いたう吹き、海の面 (おもて) ただあし―あしうなるに」〈枕・三〇六〉

I think 形容詞 cannot be used in this construction in the modern usage. See
[this](https://japanese.stackexchange.com/questions/87450/about-phrases-
like-%E5%A3%B2%E3%82%8C%E3%81%AB%E5%A3%B2%E3%82%8C%E3%82%8B?noredirect=1&lq=1)
for some other examples.

