"Before submitting the application for at least 2 months and after receiving permission for at least 3 months, there must be a deposit of
not less than 800,000 baht in a commercial bank account located in Thailand."
Albeit a translation from the official Thai Immigration site, it does say "a" bank, that would then all depend on their reading of that, does "a" mean only one, or does "a" mean however many but they must be commercial banks?
Just read your post above, so we at least know they will accept 2 from the same bank.