[IDEM libro septuagensimo quarto ad edictum. ] §44.2.5.prDe eadem re agere uidetur et qui non eadem actione agat, qua ab initio agebat, sed etiam si alia experiatur, de eadem tamen re: ut puta si quis mandati acturus, cum ei aduersarius iudicio sistendi causa promisisset, propter eandem rem agat negotiorum gestorum uel condicat, de eadem re agit.
[THE SAME, in the seventy-fourth book on the Edict.] A person is also deemed to sue concerning the same matter even if he does not bring the same action which he brought from the beginning, but brings another, provided it is nevertheless concerning the same matter. For example, if someone who was about to bring an action on mandate, when his opponent had promised him to appear in court, sues on the ground of unauthorized agency or brings a condictio concerning the same matter, he sues concerning the same matter.
recteque ita definietur eum demum 'de ea re' non agere, qui prorsus rem ipsam non persequitur: ceterum cum quis actionem mutat et experitur, dummodo de eadem re experiatur, etsi diuerso genere actionis quam instituit, uidetur 'de ea re' agere.
And it will be correctly defined in this way: that he alone does not sue 'concerning that matter' who does not pursue the thing itself at all; but when someone changes his action and sues, provided he sues concerning the same matter, even if by a different kind of action than the one he initiated, he is deemed to sue 'concerning that matter'.