I think the rationale is that since the releases of Hot Rodimus are far enough apart that the second record is warranted (2008 vs. 2011).
If the releases were closer together, say a few months, or even a year, we can assume that the parts were probably all from the same batch. It's possible that TakaraTomy cranked out "x" number of units, but only put 1/2x out on the market, not knowing how well they would sell, keeping the others for a "rainy day", or perhaps for a planned second release.
But since these Hot Rodimus releases were 3 years apart, I'm betting against this scenario.
MIKE
engledogg