AFAIK, the OVC / BKN at the end of the METAR refer to a layer being different at different parts of the airfield, IOW, in the second example it would vary between BKN and OVC. Why the first report states BKN twice I have not the faintest idea
Now to the SC and ST. I have never - so far - see any cloud type other than CBs and TCUs mentioned in a METAR. I am therefore a bit reluctant to accept this as explanation. I might actually give the guys at LOAV a call to find out.