Is zakat due this year on merchandise for which zakat was paid in 2005 and 2006, but which has not been sold? And what is the meaning of the hadith: "There is no repetition of zakat payment in charity"?

If the merchandise is for trade and zakat is obligatory on it, the majority of scholars hold that zakat becomes due on it every time a year passes and it reaches the nisab, even if it becomes stagnant. The Malikis differentiate between the "Mudeer" (active trader) who buys and sells at the current price, and thus pays zakat on his merchandise every year if it reaches the nisab, even if it is unsold, and the "Muhtakir" (hoarder) who waits for prices to rise, and for whom zakat is not obligatory until he sells and its value reaches the nisab. Some contemporary jurists have inclined towards the view of Ibn Nafi' and Saḥnun from the Maliki school, that the Mudeer's ruling becomes like that of the Muhtakir in the event of merchandise stagnation, meaning he does not pay zakat on it until he sells. This offers more ease in cases of stagnant goods. "No thani in sadaqa" means that zakat is not taken twice in one year from the same owner's wealth.