To have a qualifying low hand, there has to be at least 3 cards that are 8 or lower on the board, if there isn't there's only a high pot. The pot is split 50/50 between Hi and Lo if there there is a qualifying low hand (each pot may be split, it is common to have a low pot split)
It's also possible to win both puts with the same hand, as long as you're using 2 of your cards and 3 from the board. They could be identical, or they could be different
For example if you have 458T
and the board is A 2 3 9 Q, your A2345 could win both low and high pots