There is no indication of whether or not we already have an upgrade when looking at the upgrade cards... and apparently the cards can appear that you were given during the upgrade...
I now have duplicates of the following (non incremented) upgrades
Tinker Plus
Truly Outrageous
Elemental Shake
Friend of Metal
Can the cards for upgrades that we already have be removed from our 'deck' or at least marked somehow so that we know not to waste the imagination on them? Or do these non numbered upgrades stack?