According to WWWJDIC, ぬるい and ぬくい are both written 温い. Anthy and the iOS Japanese input systems agree. However a native speaker and the input of an electronic dictionary (広辞苑）say that 温い is read ...
Possible Duplicate: do people actually respect the nuances of 探す vs 捜す? There are many kanji that I have come across with similar meanings, and (seemly coincidentally) identical readings. ...