If the button does not physically get pressed, its value is not submitted. You would have to test the form's submission by looking at a textbox, checkbox, etc. value.
First, test if a button was pressed, then if no buttons were pressed, but information was submitted (a textbox value for instance), you choose yourself what you want the default function to be.
For instance, if you had a combo box with employee id numbers in it, a delete button, and an edit button.
Your code would look something like this:
If request("editbutton"

= "Edit" then
'allow user to edit that employee
ElseIf request("deletebutton"

= "Delete" then
'delete that employee
ElseIf request("combobox"

<> "" then
'you choose what you want to do as the default, whether it be editing or deleting
End If