maseches shabbos - Explanation of Mishna in Shabbat

The Mishna in Shabbat (1: 7) states that:

בֵּית שַׁמַּאי אוֹמְרִים, אֵין מוֹכְרִין לַנָּכְרִי וְאֵין טוֹעֲנִין עִמּוֹ וְאֵין מַגְבִּיהִין עָלָיו, אֶלָּא כְּדֵי שֶׁיַּגִּיעַ לְמָקוֹם קָרוֹב. וּבֵית הִלֵּל מַתִּירִין

Beit Shammai says we may not sell to a gentile, nor help him load, nor lift a load upon him, unless there is sufficient time for him to reach a nearby place. But Beit Hillel permits these acts.

R. Ovadiah of Bertinoro explains:

וְלֹא טוֹעֲנִין עִמּוֹ. עַל הַחֲמוֹר. וְלֹא מַגְבִּיהִים עָלָיו מַשְּׂאוֹי עַל כְּתֵפוֹ, דְּמֵחֲזֵי כִּמְסַיְּעוֹ לְהוֹלִיךְ הַמַּשְּׂאוֹי בְּשַׁבָּת

That is, these activities look as though the gentile was commissioned to perform tasks for the Jew on Shabbat.

The question is that the Mishnah is obviously discussing a case in which the enlisted activities were performed on Friday. (For if they were performed on Shabbat we would be dealing with larger problems).

If so, this ought to constitute a double rabbinic prohibition: an initial prohibition of utilizing a gentile's services to perform labor on Shabbat, and a further rabbinic decree prohibiting activities that might be construed as such. The rabbis generally do not enact such legislation (Cf. Betzah 3a).

I am familiar with textbook solutions to problems of "double enactments" but am looking for solutions raised by the commentators to this particular question.