Mallards in Garden

Hi,

Can anyone help please the last two days we have had two mallards in our garden who have mated. The problem is that other ducks keep landing in the garden and trying to mate with the female.  We keep chasing the others off but is this normal?  We have no water in our garden and I don't know what to give them to eat and there are cats around so our garden is not ideal. Are they hiding from the other ducks?!!  Any advice gratefully received!

Thank you.