Trump's first wife was Ivana. It's a Czech name. The daughter's real name is also Ivana. "Ivanka" is a diminutive form of "Ivana".
Ivanka isn`t a Czech name. "Ivanka" (Iвaнкa) is a diminutive form of "Ivanna" (Iвaннa), which is Ukrainian name. This name is widespread in western Ukraine, namely in Galicia (Lviv, Ternopil and Ivano-Frankivsk). The name is the feminine form of the masculine name "Ivan" (Iвaн) and is borrowed through the Church Slavonic mediation from the Greek "Iωαννα" (Ioanna, Ioaннa), which is formed from the masculine name "Iωαννης" (Ioan ,Ioaн). By the way, the Greek version is derived from Hebrew "יוֹחָנָן" (Johanan) - the Hebrew man's name with the meaning "God is merciful". In English we know this name as "John".