Yes, I have never seen this before either. I don't really get it.
METAR LOAV 141500Z 13012KT 5000 BR BKN007ST 04/03 Q1013 BKN
ST fairly obviously means the BKN007 is stratus base, and the BKN means it is broken. No idea why "BKN" is in there twice!
METAR LOAV 141300Z 14012KT 5000 BR BKN006SC 04/02 Q1012 OVC
OVC means the BKN006 is overcast, but why not report OVC006 in the first place instead of BKN006? In a TAF one never has OVC but in a Metar it can be used.
SC is stratocumulus.
Bookworm is the specialist on this stuff...