All records loaded (all you can see using the Table Viewer or Ctrl + T) are avaiable for all sheets in your app. But you can limit the information displayed in one sheet using objects based on one table in Sheet1 and obects based on records from the other table.
Say you have Customers and Items as tables, and two fields in each table. You can use listboxes from Customers in Sheet1 and listboxes from Items in Sheet2.
Hope that helps.