Related for Shekalim 1:6
וְאֵלּוּ שֶׁחַיָּבִין בַּקָּלְבּוֹן, לְוִיִּם וְיִשְׂרְאֵלִים וְגֵרִים וַעֲבָדִים מְשֻׁחְרָרִים, אֲבָל לֹא כֹּהֲנִים וְנָשִׁים וַעֲבָדִים וּקְטַנִּים. הַשּׁוֹקֵל עַל יְדֵי כֹּהֵן, עַל יְדֵי אִשָּׁה, עַל יְדֵי עֶבֶד, עַל יְדֵי קָטָן, פָּטוּר. וְאִם שָׁקַל עַל יָדוֹ וְעַל יַד חֲבֵרוֹ, חַיָּב בְּקָלְבּוֹן אֶחָד. רַבִּי מֵאִיר אוֹמֵר, שְׁנֵי קָלְבּוֹנוֹת. הַנּוֹתֵן סֶלַע וְנוֹטֵל שֶׁקֶל, חַיָּב שְׁנֵי קָלְבּוֹנוֹת:
These are obligated to give a kolbon [kal-bon, i.e., something "light and small," which is added to the half-shekel]: Levites, Israelites, proselytes, and freed bondsmen; but not Cohanim, women, bondsmen, and minors. If one gives the shekel for a Cohein, a woman, a bondsman, or a minor, he is exempt (from the kolbon) [as when he lent them. For since they are exempt (from the half-shekel), they are not liable for the kolbon. And if he did not lend them, but paid for them, even if he gave the shekel for one who is obligated, he is exempt from the kolbon, as explained below.] And if one gives the shekel for himself and for his friend [(This, in an instance where he lends him. He gives one shekel: a half-shekel for himself, and a half-shekel that he lends his friend)], he is liable for one kolbon. [For this tanna holds that one who gives the half-shekel specified in the Torah is exempt from the kolbon, it being written (Exodus 30:13): "This shall they give" — Exactly as this shall they give and not more, so that with two who give one shekel, only one kolbon is given.] R. Meir says: Two kolbonoth. [R. Meir holds that one who gives a half-shekel is liable for one kolbon, so that if two give one shekel, they are liable for two kolbonoth. The halachah is not in accordance with R. Meir.] If one gives a sela [a whole shekel, to the Temple money-changer], and he takes a shekel ["a shekel" here is a half-shekel, i.e., he gets back half of what he gave], he is liable for two kolbonoth. [Here the first tanna concedes that he gives two kolbonoth: one to compensate for the half-shekel that he receives from the Temple, and one because he did not give the (exact) half-shekel specified in the Torah.]