I noticed that some poison need multiple consecutive saves to cure them, so let's say a player gets poison and need to save twice to be cured. If he passes the first save the poison is there, so does he take the damage form the poison if he passes the first time?
if on his next save he does not make the DC then he takes whatever effects are listed so for example lets use a made up poison:
Strength Sap: DC 20 1/6 rounds, 2 saves, 1d4 str damage
so that once a round for 6 total rounds, if he saves 2 times he is cured.
If he saves on the first round he take no str damage, on the next round if he fails the save then he takes the 1d4 str damage. Saving only one time basically lets you "shake off" the effects for that round.