Bad Form Submit vs Not Bad Form Submit

gistfile1.html

<!--BAD-->
<!-- The following button tag will submit the form named "formName" TWICE -->
<button type="submit" onclick="$('#formName').submit()">Assign</button>

<!--Not Bad-->
<!-- The following button tag will submit the form named "formName" ONCE -->
<button type="button" onclick="$('#formName').submit()">Assign</button>