The dictionary may not be the best container for this.
It seems to me that you can have
Block1 A 3 and Block1 B 2.
By parsing the comma you could achieve this with
"Block1,A" 3 and "Block1,B" 2
but it's usually easier to use a variant array in a collection.
Dim Bc(2)
BC(0)=block.name:Bc(1)=Att.textstring:Bc(2)=count
Now you make a selset for each blockref by name,
Sort the Bcs for that block
add to the collection