Depends if there is a physical key on the other fob, if so, potentially yes.
It is unlikely anyone will know it is for your car but is it worth taking the risk? Are you covered under any sort of insurance given it is likely to be pricey - especially as you'll need new keys too.
As above,the metal key could open your car. But the lost key will be deactivated, so the alarm would go off, and could not be silenced. The car would not start.
