Calculating over two sheets

Help!

I'm sure this is probaly pretty easy but not for me!

I have a spreadsheet used for listing consumable items for photocopiers, what i would like to do is to be able to a have a second spreadsheet that whenever a product is removed from the listing it updates the second spreadsheet, which will be used for stock control and ordering replaments

The reason for two spreadsheet is firstly for security and secondly because a single item may be listed multiple times in the first list for ease of use but only listed once in the second spreadsheet. So i would need it to calculate multiple cells in the first but add the result to only one cell in the second spreadsheet

I've attached the first spreadsheet here, hope this makes sense once youve looked

many thanks