BH
The general law in the Gemara and brought in the Rambam and Shulchan Aruch is that one needs to lean while eating Matzah and drinking the 4 cups.
The question is: Is the leaning an essential condition of eating the Matzah itself [for example], and if so, if one ate matazh without leaning, which one has to go back and eat it, does one need to make another brocho of "Al Achilas Matzah", or is leaning an extra part of the Mitzvah, to emphasize the idea of freedom, and if one doesn't lean, then one still fulfills the Mitzvah of matzah, but only has to go back to eat it again to fulfill the extra concept of freedom, and thus does not need to say another brocho "Al Achilas Matzah"?