Hi,
By unchecking the "Prompt with List of values" option means you are forcing to display the LOV's from the other query prompt.
1) Whatif i donot uncheck the "Prompt with values" option for query 2 prompt?
2) Whatif i check "Prompt with values", "Select only list" option for both the prompts?
Even if all options are selected same in both the prompts still you will get the LOV's from one object only.Making a difference means you are controlling the LOV's display.
"Prompt with List of values" is one option i have suggested.even you can uncheck the "Select only list" in one query.
9.1.1 Merged prompts
When a document contains multiple data providers, any prompts that include objects with the same data type, operators of the same operator type, and that use the same prompt text are merged. When all the data providers are refreshed, a single prompt message appears for such prompts. The List of Values displayed by the merged prompt is the list associated with the object in the prompt that has the most display property constraints.
Source-Webi user guide. page 130.
http://help.sap.com/businessobject/product_guides/boexir4/en/xi4_ia_en.pdf
Amit