There is a difference between creating a new node - where the system knows exactly what the number in the name means - and copying a node whose name might mean anything. So at the moment we don't blindly assume that any number in your node name is OK to change to another name. Appending "_1" is safer in that regard, but I realise it's also annoying because it results in things like "_1_1_1_1" after a few copies. Perhaps we can change it to increment any numbers of the form "_n", so the worst that happens is you end up with "Add scalar 01_1", "Add scalar 01_2", "Add scalar 01_3" etc. I think that was the original intention when I first started adding "_1".
Matt