And also how words are borrowed and used in other languages.In France for example "bon week-end" (have a good week-end) became "bon week" with simplification in very familiar language.
And I would not be surprised people use one or the other prononciation for energy depending on which was in use in their surronding. As simple as that ? It is after all a foreign word, so I do not think they put too much thought in its use