#81 Duplicated nodes inside OOBN instance node

[Rommel Novaes Carvalho]

The first time we instantiate an OOBN class (instance node - frame), the nodes inside are duplicated. This cannot be seen now because I changed the code to not allow moving the node (therefore the nodes are on top of each other and the users do not see that there are actually two), but if we allow moving the nodes inside the frame (cannot allow moving outside the frame), this problem is going to be visible again.