I was taught that these two phrases are interchangeable and have the same meaning.

However, I recently wrote a few practice sentence using this grammar point and they were corrected to use ずには instead of ないでは

The sentences I wrote were:

１）知り合いにそっくりだったので、話しかけないではいられなかった。
２）まだ子供なので、許さないではいられなかった。

However, both of these were corrected to:

１）知り合いにそっくりだったので、話しかけずにはいられなかった。
２）まだ子供なので、許さずにはいられなかった。

I was under the impression that both were acceptable and can't find anything stating otherwise. Is there something in particular with these sentences that it can only used ずには？ Or am I completely missing something?