You can definitely get some variation on leaf shape on young plants. Think I currently have 10+ RDB's in 1 gallon pots and the leaf shape is variable one plant to the next and I guarantee they are all RDB:) As the plants grow the leaf shape will fall in line with the parent plant. I am going to do some organizing of the plants this morning so will take a group picture and post it.
EDIT..
Ok here is the picture, there are 12 RDB circled and you can see the variation in the leaf pattern.