More likely, the Americans lengthen the e in the first syllable into almost a diphthong, like /eɪ/, and shorten the "o" in the second syllable into a schwa kind of sound that can comfortably be followed by /z/. Meanwhile, in British and many European accents, the first syllable is short and strongly stressed /ɛ/, and the o is /oʊ/, and you can't add an s without contorting your mouth in some horrible way. Which is why British people are so disgusted by "Legos". Try saying it with an American accent.