You were lucky to be able to keep the old residencia cards, even though the corners were cut off.
When I changed mine for the silly big green and white paper, they said they had to keep it!
I would have liked to have kept the card myself, as proof  of identity, in my purse, instead of a big piece of paper that will soon get tatty.  After all  it had cost time and money to get that.    Rules seem to change from day to day!