I'm not a developer, but I don't think we're going to see a port for that phone. It's really not so great
My wife had one and it was driving her nuts because it was so slow. I got her an S3 (with Miui of course ) and she's loving it.
On another topic, are you from Brazil?
I'm living in Brazil now
Because HD2 was one of the best phones made by HTC. It has massive community support and lot of developers. It can have almost all androids, windows and Linux.
So yes it also has MIUI.
Duos is small, slow device without support and there's no developers that will do MIUI. Also Xiaomi won't do MIUI because they develop for hi end, top devices like S3, Note 2 or One X. Also you don't have jelly Bean so no chance for MIUI.
The hardware might be similar, but it's not identical. So you would have to make adjustments to the rom to run on the s-duos without FCs. And as Acid said above, there is no community support for the S-Duos. Therefore, nobody is willing to make these adaptations. IMHO, I think you will be happier without the S-Duos. If you really need a dual sim phone, the Grand-duos might be better since it is a dual core phone. It's already available in Brazil. Then again, I don't think we're going to see Miui on dual-sim phones so soon. It would be nice though