From their "Translator's FAQ" (which I think is meant for volunteers to help with localization): "How should I tell to pronounce DoudouLinux? In French and Chinese it is pronounced “doodoolinux”. However as the word “doodoo” has a weird meaning in slang American English, we recommend English-speakers to say it as if it was an English word, the way they prefer to say it. We also ask to not write “doodoolinux” at all t…
Looks like "dough dough" or "dow dow" to me, an English native speaker.
As a native English speaker, I would pronounce "Doudou" the same as I'd pronounce "Loulou" -- "Doo doo" and "Loo loo" respectively.