I knew previously that the designation "DT-420" had been used for two completely different Destroyer models: one from 1992/93 and one from 2002/03.
I had always heard that the second incarnation of the DT-420 was a reissue of the DT-400. Personally, I could never see it. Then I found out why. The DT-400 designation was reused in 1996 on a Japanese market Destroyer. The specs were identical to the second DT-420.
So, the second incarnation of the DT-420 (2002) is a reissue of the second incarnation of the DT-400 (1996).
I also recently discovered that the "DT-200" model designation was also recycled. The second usage, which I knew about, is from 2004. The first usage was in 1983 on a Japanese domestic model.