Technically speaking they would both be able to be read and accessed if both were in the field… this is why ISO14443 defined anti-collision features… so readers could read multiple tagged things in the field at any given time.
The problem comes from the fact that basically nobody outside of inventory control software programmers bother with that at all… they just grab the first tag ID they see and select it (select is an ISO14443 standard command)… once the reader selects a specific tag ID, the rest shut up (go into HALT state)… and this is why we can’t have nice things. This is why you can’t have multiple cards in your wallet and present them all to a transit reader or a hotel elevator or an access control reader… because programmers are lazy, and they don’t know how to do a simple goddamn for/next loop to save their lives to cycle through the cards in the field to find what they are looking for… nope… forget that noise… just select the first card and if it’s not the card we’re looking for, honk a big donkey error beep and fold your arms because we ain’t doing jack crap until you take all those damn cards the hell out of my field and try again bozo.
As you can tell, I hate this. Why bother coming up with an awesome anti-collision mechanism if nobody bothers to use it. Slap them all. Hard.