Why do both soft tokens work? (this prob doesn't belong in Forefront but it was the only selection avail)

Hi all -

Trying to wrap my head around what I suspect is an easy answer.  In light of the recent LastPass 'hack' I decided to enable two-factor authentication.  I had Google authenticator already on my iPhone but as a MSFT person decided to download and install MSFT authenticator as well.  I enrolled both applications with LastPass by scanning a bar code into each.

When I log into LastPass it prompts for my soft token code from Goodle Authenticator which works a treat.  What perplexes me is that I can ALSO use my MSFT Authenticator soft token, which is a completely different code, to authenticate.

How can I use one of two very codes to authenticate?  How does LastPass know which authenticator I'm using?  I'm very confused but I'm sure it all makes sense.  DOes anyone have a layman's explanation?