I would be thinking that milking cows would let another animal suckle. As she is being milked in the parlour she is not protecting any calf. On the other hand, suckler cows are crazy!! They are protecting their young so tend to be on the wary side of any other animals or people. Some do feed other calves, some calves we call them the "raiders" stand at the back of a cow when she is feeding her own calf and suck from there, Mrs Cow is probably confused as to whats going on but cannot see the 2nd calf behind her!!
Just wondering how this poor woman died? Was she the owner of the cows?
We have been warned as suckler farmers not to have a dog with us in the fields or even a working dog because if the dog irritates the cows they could chase it, and 9 times out of 10 the dog will run to the person its with for protection and cows could kill you as a result. Its all health and safety but good to know as much info as one can get.