I was browsing through the webpage of Japanese radicals on wikipedia (http://en.wikipedia.org/wiki/Table_of_Japanese_kanji_radicals)
74 - 月
130 - 肉
bot entries are referencing in the most right column to the respective other radical
I looked furthermore into the KANJIDIC2 kanji-lexicon file and it seems like these two kanjis-radicals are seemingly randomly assigned to kanjis.
According to this dictionary, the Kanji 育 has 肉 as radical (which it obviously has not, its 月). I made this observation in many places (I assumed all open dictionaries rely on the same public Kanji dictionary?)
<literal>育</literal> <codepoint> <cp_value cp_type="ucs">80b2</cp_value> <cp_value cp_type="jis208">16-73</cp_value> </codepoint> <radical> <rad_value rad_type="classical">130</rad_value> <rad_value rad_type="nelson_c">8</rad_value> </radical>
Does anyone know the (historical) background of this 肉／月 radical interchangeability