Hello everyone,
Is it possible to combine two reinforcing bars with the same dimensions that were generated as freeform rebar into a group so that a tag sums the number of reinforcing bars?
Hello brother did you find a way to group rebars ?
unfortunately not.
Still waiting for someone with a working idea 
This is possibly a Revit question.
See discussion here in the Revit Structure Forum → Total quantity in rebar tags
Also please review How to get help on the Dynamo forums