The Yes, and No prompts already exist in the database and make up the Bit prompt list. The Bit prompt list is used when creating a field and selecting the Field Type of Bit (Yes/No). These two prompts should not be created in the prompt tool in the database.
Fields store the Yes and No prompt values as 1 and 0 in the index column of a field. A stored value of 1 corresponds to Yes, the true value, while a stored of 0 corresponds with No, the False value. The default export for a field with the Bit type in a query will be 1 or 0. By editing the export for the field, you can put in Yes for the true value and No for the False value to export Yes or No instead of 1 or 0.
Why Not Store Prompt ID?
Storing the 1 and 0 values for Yes/No prompts is done to increase overall database performance.