US $ withdrawals from ATM

I know that some ATM's in Bishkek allow for withdrawals of US $.

If I have a US $ denominated card is the transaction done just in dollars, or is it based on converting the US amount into Som and then back again to US $. Result being a double dose of currency conversion fees?

If I end up with a double dose of fees, then I'd be better to bring a wad of US $ with me............