For standing orders there is something not correct with the way the number of items received is calculated.

A Order
1) Create a basket as standing order
2) Create an order for any record in your catalog
3) Verify quantity is 1 (always for standing orders)

B Receive
1) Receive shipment for your order
2) Make sure to change quantity received to something higher than 1
3) Finish receiving

C Verify display
1) Search for your invoice on the invoices page
2) Verify it shows quantity received as entered
3) Got to invoice details page
   /cgi-bin/koha/acqui/invoice.pl?invoiceid=1
4) Verify it still shows 1 as quantity - should show the received quantity

5) Click on the record's title to go to the detail page
6) Switch to acquistion detail tab
7) Verify it shows 1 too - should differentiate between ordered/received

I think the first (invoice) is clearly a bug, the second might be seen as a display error, but we should specify which quantity is shown and possibly add a display for ordered / received. If the status is received the info on the acq tab is definitely misleading.