Vogue
Others eat Matza on the night of the 15th of Iyar as well because just like by Pesach we bring the Korban Pesach on the 14th but only ate it at night on the 15th, so too on Pesach Sheini. The Zichron Yehuda says that the Maharam Ash (a talmid of he Chasam Sofer) would eat Matza, Maror, and a boiled egg on the night of the 15th of Iyar.
From revach.net