I have covered parts of this in my recent post 'A Single or Mirror Will, which is the best for me?'. In the instance whereby a married couple are looking into Wills online, a Mirror Will is usually created. A Mirror Will is a pair of similar Wills of which the provisions match one another. However if between you and your partner have different wishes then you would each need to make separate Single Wills.
If you make a Will but then divorce and get remarried this then cancels a previous Will unless the Will expressly states otherwise.