Date Field containing From Date and To Date as argument returns more nodes than it is supposed to

I have a date field which includes from_date and to_date.

When I create a calendar view, I can see this date field was separated into 2 fields, one is "from date" and another is "to date".

I choose only one which is "from date". however the SQL query it generates is like

**** AND ((DATE_FORMAT(STR_TO_DATE(node_data_field_my_date.field_my_date_value, '%Y-%m-%dT%T'), '%Y-%m') <= '2010-03' AND DATE_FORMAT(STR_TO_DATE(node_data_field_my_date.field_my_date_value2, '%Y-%m-%dT%T'), '%Y-%m') >= '2010-03'))

You can see although I didn't select "to date" when I add the argument, the "to date" (node_data_field_my_date.field_my_date_value2) is still used in the SQL query. The views still treat this field as a "Range" instead of a single date (from date).

My intention is to get all items which has "from date" in March, but the result is the view returns more items than it supposed to. As long as "from date" - "to date" covers any day in March, the items are returned. for example, "1/1/2010 - 4/1/2010".

This might not be a bug in Calendar module. Could anyone give me any hint how I can fix this?

Should I post this to Views issues?

Thanks!