Impossible to answer with certainty without knowing the quality of the Divx transfer such as it’s bitrate and resolution. Having said that, you’ll almost certainly end up with better quality from the DVD itself. If the Divx file was very high bitrate and 720x480 resolution, you might get a better result from the Divx file, but neither of those are likely at all.
One problem with converting from the Divx file to a DVD format is that you will then have done two conversions, from DVD to divx back to DVD, while with the DVD it would only be one encoding step. It’s always bad to go through multiple encodings if you can avoid it, as well as changing resolutions as will likely be the case (the divx file has probably been lowered in resolution from the original DVD). Without getting overly complicated about it, you’ll almost certainly be better off from the DVD. I could then get into how using something as DVD Shrink with Deep Analysis and AEC or DVD Rebuilder would yield even better results than Clone, but I won’t go there.
In the end, do whatever you’re happy with. If you’re happy with two converted Divx movies onto one DVD, that’s fine. My standards are higher than that and I would not be happy with the resulting quality, but if you are happy with it, great. If that’s the case, you should just get a DVD player that plays Divx files such as a Philips DVP642 and then you can just burn several divx files straight to a DVD with zero conversion.