If a letter has a shaddah on it, do we do the shape of the harakah on our lips for both the letters or only the second letter?

Question
If a letter has a shaddah on it, do we do the shape of the harakah on our lips for both the letters or only the second letter? For example, Surah al-Baqarah: ayah 13 (kamaa aama assufahaa') and ayah 18 (summum bukm)

Answer
A shaddah represents two of one letter, the first of the two saakin and the second voweled with the vowel on the shaddah.   We should only have mouth and jaw movement for the vowel on the second part of the shaddah.  During the first part of the shaddah (the saakin letter) we should have our mouths in a neutral position.