I get some informations about the Thommen/Thomman surname on a Swiss site :
"Joh[an]s Toman 1362 Zollikon Hans, Heini and Ruedi Thomann 1401 citizens to Zurich @ eingedeutscht with the education syllable mann < lat./griech.Thomas's < hebr. thôcamîm ' twins ', after the Apostel Thomas, in the Middle Ages of one of the most popular holy names, patron of the building and master carpenters."
The family of Durst Thommen from Basel, Switzerland, arrived on 16 SEPT 1736 in Philadelphia onboard the Ship Princess Augusta. They settled in Ephrata, Lancaster Co., PA. Durst's son Martain changed his surname to Thomas. A son of Martain, Jacob, is sometimes found as Jacob Dome (in his will).