Can dogs be identical twins? This is an interesting question! Well, if we think about it, all puppies are all fraternal twins, triplets etc. since they are all born the same day, but that though doesn't make them "twins" in the real sense of the word.
In order to be really twins, dogs would have to come from the exact same fertilized egg, that splits into two separate embryos. This means that if the split takes place later, they would share one placenta with their umbilical cords attached to it.
There are rare reports of dogs being genetically identical, and in order to verify this, DNA testing would be required.
Below is the sensational news about a truly verified case of real, identical twin pups being born from an Irish wolfhound. https://www.livescience.com/55978-identical-twin-irish-wolfhound-puppies-confirmed.html