I think this solution is good:
@app.route('/contact', methods=['GET', 'POST'])
def contact():
form = ContactForm()
if form.validate_on_submit():
if form.submit.data:
pass
elif form.submit2.data:
pass
return render_template('contact.html', form=form)
Form:
class ContactForm(FlaskForm):
submit = SubmitField('Do this')
submit2 = SubmitField('Do that')