we just had a new AC system installed in my florida house. the unit is in the garage, and the air handler is vertical with the evaporator on top.
the unit he removed had 2 condensate lines: one that drips outside on to the lawn and a second on that points at the floor but never dripped.
the new unit is only connected to the outside drain.
should the new unit have 2 drain lines?
No, probably not. The reason there are two lines is in case one gets clogged up, the second one will be used as a backup.
The reason for the backup line is if the unit is in the house, you absolutely don't want a clog in one drain line to cause water to drip out of the unit and get all over your house. Since it is in the garage though, it probably just doesn't matter much if you get water on the garage floor. Which is probably why the installer didn't bother installing a backup line (which it sounds like just drained onto the floor anyways)
