I don't think it's called anything. If the same melody were used, but with different lyrics, it *could* be called "parody" -- unless, as in English balladry for example, it is simply usual practice to keep the identities of texts and tunes separate, such that texts can be sung to various tunes and tunes do work for several texts.

I don't hear that these are the same. I'd rather hear a calypso or mento rendition of "Donkey City" to compare. If Baba Brook's band is calling their ska track "Donkey City," then the song they have in mind is Donkey City. In other words, if you compare calypso versions of Yankee Dollar and Donkey City, and they turn out to have the same melody, then you have a situation of parody *or* re-use. However, Baba Brooks (the Skatalites) is just playing an instrumental version (worked into the jazz-like format of ska) of "Donkey City," I presume.

IMO ska didn't have much that was truly (uniquely) in common with calypso/mento, except for the fact that old mento songs' melodies (and chord progressions) were sometimes set to the ska rhythm. So whatever the Donkey City melody was, it has been twisted and contorted into having a very different "feel" in this ska rendition.

Incidentally, if you listen to "Part II" of Baba Brooks' Donkey City, you can hear some really brilliant drumming by Lloyd Knibb, the drummer who more or less invented ska, who just passed away in May 2011.