In the song Yom Shabbaton it says:
חָקוּק בִּשְׁנֵי לֻחוֹת אֲבָנִים
Translated as:As is engraved in the two Tablets of stone
The text of this song seems to imply that the commandment of shabbos is on both tablets of the Luchos while everyone who knows the basic form of the ten commandments knows its only on one side of the Luchos as yo can see in any picture of the Luchos?