First of all, I'm not sure if the question is appropriate here or if it should be posted in linguistics, but since Bavarian is listed as language under the "Dachsprache", I think it's appropriate.
I tried to research it, but I didn't come up with anything that would provide me more evidence.
"In oana dua" is an interesting expression, because the word "dua" is always ever only found in this context. So the question is, where does it come from?
I have 3 leads that seem logical to me:
- from Latin "durare", compare to English "duration", which would make the sentence "in one duration"
- a noun formed from the Bavarian "i dua" ("I do"), which would mean make the sentence "in one doing"
- from "tour" (In Bavarian "T" often turns into "D", so pronounced "dua")
Perhaps there are more possible explanations, so if you have one, please add them.
Edit: Since I have been asked to add a translation and examples:
ENG: all the time
GER: die ganze Zeit
BAR: "In oana dua hód'a gmosad."
GER: "Die ganze Zeit hat er gemeckert."
ENG: "He complained all the time."
BAR: "Des géd haid šo in oana dua so."
GER: "Das geht heute schon die ganze Zeit so."
ENG: "It's been going on like this the whole day."