An interesting characteristic of Bamum orthography is the development of a pleonastic way of writing, whereby a single syllable can be written using more than one sign, particularly CV+V. That is to say, an open syllable can be followed by an independent vowel sign, without lengthening the vowel or altering the weight of the syllable. For example, the Bamum word for 'marriage', [lam], is written with three characters, la+a+m, but only the first and third characters are pronounced, the second 'a' being somewhat redundant. The reasons for this are unknown.
Coulmas, Florian. 1999. The Blackwell Encyclopedia of Writing Systems. Blackwell Publishing. Oxford. 37-38