With Calc I created a Document: in  the 1st page (or sheet or table, as you 
call  it) I put my data; in the 2nd page I created some graphic with this data. 
Then in the 3rd page I put some new and different data which have nothing to do 
with the 1st page data and with the graphics in the 2nd  page. I save 
everything and close the window.
Next time that I open this document, I find that my graphic look completely 
different from the previous time: I check the 'origin of the data' and I find  
that this time Calc has opened my graphics using the 3rd page datas!! I've 
found more than once, and it happened several times: it seems that Calc uses 
the page with data that is more close (I mean more close in the bottom 
orizontal bar) to the  page with the graphics.