A better male "equivalent" for Nechama would be Nachum.

Another reason for similar sibling names:   There was an ancestor named Chayim.  Descendants wanted to name their child after him, but the child was a girl, and they had no way of knowing if they would have another chance, so they named the girl Chayah.    Then, several years later, they had a boy,  Given this opportunity to "do it right", they called him Chayim.
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Fredel Fruhman
Brooklyn, New York, USA