Form - ID field changes name automatically

I like to double check my forms for the accessibility issues. I am using
MySQL/PHP on a WindowsXP pro machine.

When I go through the form by clicking on the form element, such as the text
box, so I can see the line of code associated with it, THEN I move to the next
form element. I looked back to the original one and the Id changes from
BusinessLocation to BusinessLocation2. If I repeat that process it changes to
BusinessLocation3.

<input name="BusinessLocation" type="text" id="BusinessLocation" size="50">

Any idea why this is happening or what DW setting I can change so it won't
rename the id on me?

Thanks. Leesa