hi there
two tide changes sounds a bit strange. Most places have two low and two high tides per day and tides change every 6 hours on average.
Which exact location are you looking at - what is the name of the tide station you are viewing here on fishingreminder?
Which site were you comparing to? Do you have a link?
We can investigate this, if you send through some more details.
cheers
If people concentrated on the really important things in life, there'd be a shortage of fishing poles.